Appendix 1: Brief History of Key Developments in Ground Engineering

Brief History of Ground Engineering Hood and Brown (1999), Hoek (2007) and Brown (2011) describe developments in ground Underground mining dates back to at least engineering in general dating from the 1800s. 40,000 BC when Neanderthal Man mined hae- The authors note that technical reports dating matite in Swaziland (Gregory 1980). The earliest from the nineteenth century were based mainly known examples of artificial ground support are on qualitative visual observations and it was only pillars constructed from piles of stones in mala- towards the end of the nineteenth century that chite mines worked by the Egyptians in the Mid- mechanisms of ground pressure and deformation dle East from about 1350 BC to 1000 BC (Shaw began to be postulated. During the first half of the 2006). Agricola (1556) described how timber twentieth century, technical reports that treated posts, caps, lagging and lateral restraints were rock as an engineering material started to appear. used in the sixteenth century to provide support Laboratory studies using both photoelastic and for roadways in metalliferous mines. material models of rock were reported, with the Although the origins of rock mechanics can be production of scientific and engineering informa- traced back to the work of Coulomb in 1773, tion about rock properties and the design and subsequent developments in this field were spo- stability of structures in rock accelerating rapidly radic and mostly confined to laboratory studies. during the 1930s. Some of the first investigations of a pseudo- There is mention in the literature of rock scientific nature into ground control were bolting having been practiced in the USA conducted in Belgium in the 1820s, when a Com- before the turn of the twentieth century mission was established to investigate surface (Gardner 1971) but it was not until 1943 that cracks and damage to buildings caused by literature described the planned systematic use ground subsidence over coal mine workings in of rock bolts. This was at a lead mine in the the city of Liege. By 1880, a number of empiri- USA. By 1949, rock bolts were being used in cally based theories to account for vertical dis- more than 200 mines in the USA, including placement above mine workings had been coal mines (Bieniawski 1987). Rock bolts developed in Belgium, Germany, France, Great were tried for the first time in Australian coal Britain and the USA. Whittaker and Reddish mines in 1949, in the Greta Seam at Elrington (1989) provide fuller accounts of the evolution No. 2 Colliery in NSW (Gardner 1971). of subsidence engineering. Benefits were immediate (McKensey 1952)

# Springer International Publishing Switzerland 2016 567 J.M. Galvin, Ground Engineering - Principles and Practices for Underground Coal Mining, DOI 10.1007/978-3-319-25005-2 568 Appendix 1: Brief History of Key Developments in Ground Engineering and rock bolts were progressively introduced Salamon was to report later that he had come to into the NSW coal industry. the conclusion in the late 1950s that mathematical The coining of the term ‘strata control’ is modelling is essential in mining because the num- attributed to the First International Conference ber of variables is so great that it is entirely imprac- on Rock Pressures held in Liege, Belgium in tical to explore experimentally their full range of 1951 (Bieniawski 1987). The first annual US influences. Moreover, no mathematical model is Rock Mechanics Symposium was held in 1956. sufficiently general or complete to incorporate all Nevertheless, by the end of the 1950s, there was physical aspects of the rock mass; its geometry, still no qualitative rock mechanics design behaviour and support; and the mine layout. There- method in general use by the mining industry, fore, field experiments are vital in evaluating the with researchers in the intervening years being efficacy of mathematical models (Salamon 1989). hampered by a lack of data relating their research Brown (2011) restated his view that, by the results to the physical reality in the field early 1960s, the subject of rock mechanics, if it (Salamon 1988). wasn’t yet fully established, was well on its way The laboratory study of the mechanical to becoming established as an identifiable scien- properties of rock was already reasonably well tific and engineering discipline. Brown cites the advanced but, apart from notable exceptions, lit- appearance of specialist journals, conferences tle was known about the behaviour of rock and societies to support his view, noting that the around mining cavities. In Britain, Professor first issue of the first specialist journal devoted to E.L.J. Potts, who headed a large geomechanics rock mechanics and rock engineering was research group at the University of Newcastle published in Vienna in 1929. upon Tyne, argued at the time that strata control One of the early handbooks relating to the problems will never be understood properly application of rock mechanics in coal mining unless meaningful field measurements are was produced in 1976 by Salamon and Oravecz undertaken (Salamon 1989). A major campaign for the South African Chamber of Mines of field measurements of strains, displacements Research Organisation (COMRO) (Salamon and and stresses was initiated, necessitating the Oravecz 1976). The Foreword to that book development of suitable instrumentation reports that up until some 10 years earlier, rock (Potts 1957). mechanics and strata control in underground coal The failure of the Malpasset Dam in France in mines were based largely on rule of thumb 1959, the collapse of Coalbrook Colliery in methods and some guess work. South Africa in 1960, and the overtopping of During the period from 1960 to 1995, there the Vajont Dam in Italy due to a landslide in was a concerted effort to place ground control in 1962, resulted in a combined loss of over 3500 underground coal mining on a firm scientific and lives, with these tragedies leading to major engineering footing through the establishment of advances in rock mechanics. In 1962, the Inter- a number of large research institutions in the national Society for Rock Mechanics was major coal producing countries of the world. In established in Salzburg. The PhD thesis of the Preface to the 1986 edition of Coal Mine Miklos Salamon, submitted to the University of Ground Control, Peng expressed the view that Durham in the same year, appears to have there was a gap between theory and practice that contained the first proposal for numerical analy- needed bridging in order to advance the ‘art’ of sis on the basis of mathematical models ground control into the ‘science’ of ground con- (Salamon 1962). trol and that this gap was the most urgent and Appendix 1: Brief History of Key Developments in Ground Engineering 569 challenging task facing rock mechanics the rock itself and by the load-deformation engineers (Peng 1986). As of 1997, Hudson and characteristics of the surrounding rock mass, Harrison were still of the opinion that although or loading system. This, in turn, has led to a rock mechanics and the associated principles are mechanistic understanding of controlled and a science, their application is an art (Hudson uncontrolled rock failure and recognition that and Harrison 1997). rock still retains a substantial load carrying Hood and Brown (1999) considered that the capacity after being loaded beyond its point renaissance period, in the sense of a period of of maximum resistance to deformation. vigorous artistic and intellectual activity, for the • Recognition that the load-deformation field of mining rock mechanics, and perhaps rock behaviour of a rock mass beyond the fractured mechanics generally, was from about the begin- skin of an excavation can be simulated ning of the 1960s to about 1983. While the approximately by a linear elastic model. knowledge base created during this renaissance • Advances in computational power and period has been extended, the main emphasis in developments in numerical modelling soft- the post-1983 era has been in the application of ware codes, thereby enabling increasingly the knowledge. complex mining situations to be simulated. The 1990s and early 2000s were characterised • Developments in understanding the mechan- in the western world by the closure of most of the ics of blocky rock masses, in methods of anal- renowned mining research establishments and ysis for blocky jointed rock, and in applying the demise of a number of minerals tertiary edu- outcomes to excavation engineering and cation institutes (Wagner 1999; Wagner and ground support and reinforcement design. Fettweis 2001; Galvin and Carter 2003). Many of these, such as the South African Chamber of These theoretical advances have been Mines Research Organisation and the National complemented with advances in field instrumen- Coal Board in the UK, had a strong basic and tation and monitoring, support technologies and applied research focus on fundamental ground mining techniques, with notable applications in engineering principles. During the same period, underground coal mining being: there was a significant growth in ground engineering research in China. • techniques for measuring in situ stress; Table A1.1 summarises the more important • microseismics to detect failure deep within developments, milestones and points of note the rock mass; related to underground mining and, in particular, • microprocessor monitoring of instrumentation ground engineering since 1770. In the last and mining equipment to provide continuous 50 years, advances in rock mechanics largely and real time information as to ground response; account for advances in the theoretical knowl- • technologies for internally reinforcing the edge base that underpins ground control. The rock mass to improve its self-supporting more important of these advances have been: capacity; and • static analysis, kinematic configuration, and • Recognition that the mode of in situ rock control and monitoring of longwall powered failure is controlled by both the properties of supports. 570 Appendix 1: Brief History of Key Developments in Ground Engineering

Table A1.1 Timeline of some of the more important developments, milestones and points of note from 1770 related to underground mining and, in particular, ground engineering 1770 Longwall mining introduced in Britain (hand mining on the advance) 1842 Employment of women and children in underground mines banned in Europe 1850 Compressed air first used underground 1851 Great Britain was the world’s largest coal producer, producing about 60 million tonnes per annum Following the Hartley Colliery disaster of 1862, all coal mines in Great Britain were required to have two separate shafts or other means of access and egress The annual death rate from falls of ground in Great Britain underground coal mines was 2.02 per 1000 persons employed underground (Siddall 1915) Annual death rate from all causes was 4.29 per 1000 (Atkinson 1895) 1860s Pneumatic drill developed and applied to mining Dynamite invented (1863) Backfill used to control surface subsidence (1864) Development of the first mechanical coal cutter, introduced in Great Britain (1868) 1894 First mechanisation introduced into the Newcastle Coalfield, Australia, at Hetton Colliery in the form of a Jeffrey pneumatically powered coal under-cutting machine 1895 At a depth of 970 m, the 180 Gold Mine in Bendigo, Victoria, Australia, was reported to be the deepest mine in the world Falls of ground accounted for 40.5 % of all deaths in Great Britain underground coal industry, nearly double that of the next highest cause, namely explosions (Atkinson 1895). This equated to some 400 deaths from falls of ground 1908 The annual death rate from falls of ground in underground coal mines in Great Britain was 0.74 per 1000 persons employed underground (Siddall 1915) A committee appointed to the ‘Inquiry into the Causes of and Means of Preventing Accidents from Falls of Ground, Underground Haulages, and in Shafts’ found that the longwall system was the best method of working coal seams (Siddall 1915) 1913 Falls of ground accounted for 620 deaths and 62,094 accidents in underground coal mines in Great Britain, corresponding to an annual death rate of 0.68 per 1000 persons employed underground (Siddall 1915) 1943 Apparent first mention in literature of the systematic use of rock bolts, being at a lead mine in the USA 1949 Rock bolts in use at over 200 mines in the USA Rock bolts trialled for the first time in an Australian coal mine, at Elrington Colliery, NSW Early 1950s First continuous miner in Australia, a Joy 1CM, was installed at Newstan Colliery, NSW Rock bolting progressively introduced into Australian coal and metalliferous mines Nearly all longwall operations in Great Britain and Europe fitted with hydraulic powered supports Mid 1950s Shotcrete introduced into the underground construction industry in the mid 1950s (in Europe) Borehole extensometers developed and used extensively Early to mid A range of closed-form solutions existed for stress induced around underground excavations of 1960s simple shapes Problems involving complex shapes were studied using photo-elastic models Site characterisation (rock mass classification) started to be used in some underground mines First cable bolts introduced in underground mining in metalliferous operations. This was in South Africa and Canada First shortwall mining system, comprising hydraulic supports and a continuous miner was installed in Australia at Burwood Colliery First trials of longwall mining system comprising self advancing powered supports, AFC and a coal plough undertaken in Australia at Coalcliff Colliery Techniques developed to monitor seismic response of rock mass to mining activity Late 1960s Electrical resistance analogue computer developed Early 1970s Cable bolts introduced in underground metalliferous mining in Australia Servo-controlled rock testing machines developed Mid 1970s Rock mass classification systems used extensively in the metalliferous mining sector Microseismic monitoring implemented to determine the location and magnitude of failures within the rock mass (continued) Appendix 1: Brief History of Key Developments in Ground Engineering 571

Table A1.1 (continued) 1984 Mobile breaker line supports (mobile roof supports) introduced in pillar extraction 1990s Rapid uptake in use of remote controlled mining equipment in all forms of underground mining Cable bolts utilised as primary support in underground coal mining Closure of world-renowned ground control research organisations and tertiary minerals education institutions in the western world and an expansion of ground control research in China 2000–present Continuing step advances in computational techniques Continuing advances in ground support and reinforcement systems Periods of up to several years without a fatal fall of ground in Australian underground coal mines

McKensey, S. B. (1952). Roof bolting in bord and pillar References workings. Elrington and Hebburn No. 2 Collieries. Supplement to AusIMM Bulletin, Feb 1952, 40. Agricola, G. (1556). De Re Metallica (H. C. Clark Peng, S. S. (1986). Coal mine ground control (2nd ed.). Hoover & L. H. Hoover, Trans.). New York: Dover Wiley. Publications. Potts, E. L. J. (1957). Underground instrumentation. Atkinson, W. N. (1895). Presidential address to the Quarterly, Colorado School of Mines, 52(3), 135–182. Federated Institute of Mining Engineers. The Science Salamon, M. D. G. (1962). The influence of strata move- and Art of Mining, V(21). ment and control on mining development and design. Bieniawski, Z. T. (1987). Strata control in mineral engi- PhD thesis, University of Durham, Durham. neering. Rotterdam: A.A. Balkema. Salamon, M. D. G. (1988). Developments in rock mechan- Brown, E. T. (2011). Fifty years of the ISRM and ics: A perspective of 25 years. Transactions of the associated progress in rock mechanics (pp. 29–45). Institution of Mining and Metallurgy, 97, A57–A68. Paper presented at the 12th congress of the Interna- Salamon, M. D. G. (1989). Significance of strata control tional Society Rock Mechanics, Beijing. Taylor & to the safety and efficiency of mining (p. 9). Paper Francis Group. presented at the 8th international strata control confer- Galvin, J. M., & Carter, R. J. (2003). Strategic review of ence, Dusseldorf. Minerals Council of Australia tertiary education Salamon, M. D. G., & Oravecz, K. I. (1976). Rock initiatives (pp. 45). Canberra: Minerals Council of mechanics in coal mining (P.R.D. series no. 198). Australia. Johannesburg: Chamber of Mines of South Africa. Gardner, F. J. (1971). History of rock bolting. Paper Shaw, T. (2006). History of mining. Personal presented at the symposium on rock bolting, communication. Wollongong, 2–0 to 2–14. Illawarrra Branch Siddall, F. N. (1915). Some notes on supporting roof in AusIMM. coal-mines. Transactions of the Institute of Mining Gregory, C. E. (1980). A concise history of mining. Engineering, XLIX(Part 2), 266–283. Oxford: Pergamon. Wagner, H. (1999). How to address the crisis of mining Hoek, E. (2007). The development of rock engineering engineering education in the Western World. Mineral (E. Hoek Ed.). Rocscience. Resources Engineering, 8, 471–481. Hood, M., & Brown, E. T. (1999). Mining rock mechan- Wagner, H., & Fettweis, G. B. L. (2001). About science ics, yesterday, today and tomorrow (pp. 1551–1576). and technology in the field of mining in the Western Paper presented at the 9th congress of the International World at the beginning of the new century. Resources Society Rock Mechanics, Paris. A.A. Balkema. Policy, 27(3), 157–168. Hudson, J. A., & Harrison, J. P. (1997). Engineering rock Whittaker, B. N., & Reddish, D. J. (1989). Subsidence. mechanics. An introduction to the principles (1st ed.). Occurrence, prediction and control. Amsterdam: Pergamon Press Inc. Elsevier. Appendix 2: Equivalent Moduli for a Stratified Rock Mass

Equivalent Elastic Moduli where 0 ν and ν are Poisson’s ratios in the plane of Solution for the equivalent moduli of stratiﬁed transverse isotropy to a stress acting parallel and rock mass (Salamon 1968). normal to it, respectively. À À ’ 0 If Eeq n and Eeq p are equivalent Young s Ej, νj, hj ¼ Elastic modulus, Poisson s ratio, moduli in the plane of transverse isotropy and thickness of jth layer, respectively and in the direction normal to it, respectively, T ¼ totalstratathickness then: Φ ¼ hj X j T ΦjEj À ν2 1 1 j ¼ X X ðA2:1Þ E À ΦjEj ΦjEj eq n Reference 1 þ νj 1 À νj ! hi Salamon, M. D. G. (1968). Elastic moduli of a stratiﬁed 1 P 1 0 2 E 1 ¼ Φ À ν : j: rock mass. International Journal of Rock Mechanics j 0 2 j 0 E À E E 1 À ν eq p 0j j1 j and Mining Science 5(6), 519–527. 0 2 P ν Ej j B Φj: 0 : Àν C B E 1 j C þ2B P j C @ ΦjEj A 1 À νj ðA2:2Þ

# Springer International Publishing Switzerland 2016 573 J.M. Galvin, Ground Engineering - Principles and Practices for Underground Coal Mining, DOI 10.1007/978-3-319-25005-2 Appendix 3: Basic Statics Formulations for a Clamped and a Simply Supported Beam Subjected to Transverse Load

Table A3.1 Tabulation of symbols Terminology Symbol Parameter p point of interest s span of beam (m) x longitudinal distance from end of beam to point p (m) t thickness of beam (m) z normal (transverse) distance from neutral axis to point p (m) q load per unit width acting on beam (N) γ unit weight of beam (N/m3)

δx deﬂection of beam at a distance of ‘x’ from the beam end (m) E elastic modulus of beam (N/m2) I moment of inertia (m4)

Mx bending moment at a distance of ‘x’ from the beam end (N m)

σx bending stress at a distance of ‘x’ from the beam end (N/m2)

Vx shear force at a distance of ‘x’ from the beam end (N) 2 τxz shear stress generated by shear force Vx (N/m )

# Springer International Publishing Switzerland 2016 575 J.M. Galvin, Ground Engineering - Principles and Practices for Underground Coal Mining, DOI 10.1007/978-3-319-25005-2 576 Appendix 3: Basic Statics Formulations for a Clamped and a Simply Supported Beam ...

Clamped Beam

Table A3.2 Formulations and maximum values for deformation parameters associated with a uniformly loaded, clamped beam of rectangular cross-section and unit width Parameter Formula Maximum value δ 2 2 4 Deﬂection x qx ðÞs À x Eq. A3.1 γs s Eq. A3.2 δ ¼ at x 24EI 32Et2 2 γ 2ðÞÀ 2 ¼ x s x 2Et2 Bending Moment qðÞ 6sx À 6x2 À s2 Eq. A3.3 qs2 Eq. A3.4 Mx ¼ À atabutment Mx 12 12 Moment of Inertia bt3 Eq. A3.5 – – I ¼ 12 t3 ¼ forunitwidth 12 Bending Stress σ M z 12M z Eq. A3.6 2 γ 2 Eq. A3.7 x σ ¼ x ¼ x qs ¼ s x 3 atabutment ÀÁI t 2t2 2t Shear Force V ¼ s À Eq. A3.8 qs Eq. A3.9 x Vx q 2 x atabutment 2 Shear Stress τ 3V t2 À 4z2 Eq. A3.10 3qs 3γs Eq. A3.11 xz τ ¼ x ¼ inneutralaxisatabutments xy 2 t3 4t 4

Simply Supported Beam

Table A3.3 Formulations and maximum values for deformation parameters associated with a uniformly loaded, simply supported beam of rectangular cross-section and unit width Parameter Formula Maximum value 3 2 3 4 Deﬂection δx qxðÞ s À 2sx þ s Eq. A3.12 5γs s Eq. A3.13 δ ¼ at x 24EI 32Et2 2 γ ðÞ3 À 2 þ 3 ¼ xs 2sx s 2Et2 2 Bending Moment Mx qxðÞ s À x Eq. A3.14 qs s Eq. A3.15 Mx ¼ À at 2 8 2 Moment of Inertia bt3 –– – I ¼ 12 t3 ¼ forunitwidth 12 Bending Stress σ M z 12M z Eq. A3.16 2 γ 2 Eq. A3.17 x σ ¼ x ¼ x 3qs ¼ 3 s s x 3 at ÀÁI t 4t2 4t 2 Shear Force V ¼ s À Eq. A3.18 qs Eq. A3.19 x Vx q 2 x atabutment 2 Shear Stress τ 2 À 2 Eq. A3.10 3qs 3γs Eq. A3.11 xz τ ¼ 3Vx t 4z ¼ xy 2 t3 4t 4 inneutralaxisatabutments

1. Each beam is homogenous, isotropic and elastic. Beam Loaded by a Less Stiff Beam 2. The two beams are of equal width, b, and length, l. The analysis of the interaction between two beams 3. The cohesion and friction between the two of rectangular cross-section where the lower beam beams is zero. is stiffer and therefore loaded by the upper beam, 4. The deﬂection of the two beams is equal over is based on the following assumptions: the full length of the beams. Appendix 3: Basic Statics Formulations for a Clamped and a Simply Supported Beam ... 577

3 5. The upper beam loads the lower beam with a 0 E I ðÞq þ q E t ðÞq þ q q ¼ q þ Δq ¼ l l l u ¼ l l l u uniform load per unit length. l l þ 3 þ 3 ElIl EuIu Eltl Eutu 6. The lower beam supports the upper beam with ðA3:15Þ an equal load per unit length. Substituting Eq. A3.12 into Eq. A2.1 gives: The deﬂection of the two clamped beams at ðÞþ 2 any point, x, along the length of the beams is ql qu x 2 δl ¼ δu ¼ ðÞl À x ðA3:16Þ given by: 24ðÞElIl þ EuIu ðÞþ Δ ÀÁ ql q 2 2 Since δl ¼ δu ¼ x ðÞl À x 24ElIl ¼ ρ ðÞq À Δq ÀÁ ql lgbtl ¼ u x2 ðÞl À x 2 ðA3:12Þ ¼ ρ 24E I qu ugbtu u u 3 btl Il ¼ where 12 bt3 subscripts ‘l’ and ‘u’ denote lower and upper I ¼ u u 12 beam, respectively Δ q = load transfer to lower beam Then Since Eq. A3.12 holds true for all values of x, gðÞρ t þ ρ t it follows that δ ¼ δ ¼ ÀÁl l u u x2ðÞl À x 2 ðA3:17Þ l u 3 þ 3 2 Eltl Eutu ðÞþ Δ ðÞÀ Δ ql q ¼ qu q ð : Þ A3 13 Equation A3.17 can be used to estimate the aver- 24ElIl 24EuIu age load on the lower stratum. It is likely to be and so conservative because it takes no account of resistance to bending provided by friction between q E I À q E I Δq ¼ u l l l u u ðA3:14Þ layers and, therefore, numerical modelling is E I þ E I l l u u advisable in high consequence situations. Therefore, new loading on lower beam is Appendix 4: Foundation Behaviour

Introduction Fundamentals

In this text, a coal pillar is considered to consti- Undrained and Drained Behaviour tute a footing, with the strata immediately above and below the pillar constituting foundations. The presence of water significantly influences the All strata comprising foundations are referred behaviour of foundation materials, especially to generically as layers. The term soft refers those that are soil-like or of low strength. Settle- to materials that are more soil-like and homo- ment and ultimate bearing capacity are a function genous with little in the way of defects, so that of this behaviour. the low uniaxial compressive strength (UCS) The strength of a dry soil mass is due to: of these materials is due to the low strength of the intact material. The term weak refers • adhesion between particles; and to materials that are not necessarily homo- • friction between particles. genous and have a low strength, typically in a UCS range of 0.5 to 10 MPa, as a result of the Soil behaviour can be described by the Mohr very low strength of the intact material and/or failure criterion. Sand-based soils are because of a significant density of lower strength characterised by relatively low cohesion and rel- defects. atively high friction whilst the reverse is gener- Civil engineering foundation behaviour ally true for clay-based soils. Figure A4.1 principles are discussed under the headings of illustrates the effect of saturating a soil-like material. It is assumed that the presence of • Settlement water does not affect the cohesive strength of • Ultimate Bearing Capacity the soil. When the material is loaded, the increase

• Creep in normal stress, σn, across the particles is • Rebound (swell) opposed by an increase in hydrostatic pressure, u, which acts to keep the particles apart. The 0 The terms creep and swell have different actual or effective normal stress, σ n,ina meanings in civil engineering foundation theory saturated material is given by Eq. A4.1. to their colloquial uses in underground coal σ0 ¼ σ À ð : Þ mining. n n u A4 1

# Springer International Publishing Switzerland 2016 579 J.M. Galvin, Ground Engineering - Principles and Practices for Underground Coal Mining, DOI 10.1007/978-3-319-25005-2 580 Appendix 4: Foundation Behaviour

consolidation is also low. Therefore, this material is slow draining. However, whilst a rock-like material may have the same low permeability as a clay, its compressibility is likely to be two or three orders of magnitude lower. This means that the coefficient of consolidation for rock-like material is two to three orders of magnitude higher than that of a clay material of the same permeability and, hence, that pore pressures will dissipate 100 to 1000 times quicker than in the clay material. This is a critical consideration in coal mining environments because foundation materials can cover the full spectrum from clay Fig. A4.1 Normal and hydrostatic stress components in a through to massive, strong rock. Therefore, saturated soil-like material lithologies and material properties need to be well understood when applying civil engineering bearing capacity approaches to the design and An increase in load acts to force the particles assessment of coal pillar foundations. closer together. This is resisted if pore water The overall effect of this behaviour is that fast cannot be immediately dissipated, resulting in draining materials are considered to behave in a some or all of the additional load being carried drained manner when loaded, with the result that by the incompressible pore water. The time taken the predominant frictional strength increases for this pressure to dissipate is determined by its with increased loading. On the other hand, slow coefficient of consolidation, Cv, and the distance draining materials such as clay are considered to that the pore water has to travel through the behave in an undrained manner when loaded and, material before it reaches a free draining surface. since their strength is attributable primarily to Coefficient of consolidation is defined by cohesion, they exhibit little change in strength Eq. A4.2, which shows that it is a function of with increased loading. the coefficient of permeability, or hydraulic conductivity, K, of the material and the compressibility of the material as described by the Consolidation coefficient of volume compressibility, mv. The material is said to be in an undrained state until In the process of draining, particles move closer such time as pore water pressure is restored to a together as pore water pressure is dissipated, with steady state, when it is then referred to as being in consolidation resulting in a progressive increase in a drained state. shear strength due to increase in effective stress and ÀÁ increased friction between particles. Consolidation ¼ K 2= ð : Þ Cv γ m s A4 2 settlement is initially proportional to the square root mv w of time, before transitioning to being exponentially- where based in later stages. Therefore, it is common practice to base consolidation analysis on the time taken K ¼ hydraulic conductivity (m/s) to reach 90 % or 95 % consolidation. The relation- 2 mv ¼ coefficient of volume compressibility (m /N) ship between time and consolidation for situations 3 γw ¼ unit weight of water N/m where pore pressure is initially uniform in a consolidating layer is given by Eq. A4.3. In the case of a clay material, permeability is 2 low for a given value of coefficient of volume H Tx ¼ TFxðÞ ðA4:3Þ compressibility and so the coefficient of Cv Appendix 4: Foundation Behaviour 581 where inelastic component. The elastic component comprises the displacement, or strata compres-

Tx ¼ time to reach x% consolidation (seconds) sion, that occurs in response to the increased TF(x) ¼ time factor associated with x% stress induced in the roof and floor strata when consolidation a pillar is formed. The inelastic component of ¼ 0.196 for 50% consolidation immediate settlement arises if, during the process ¼ 0.818 for 90% consolidation of draining, the soil structure goes into yield (but ¼ 1.125 for 95% consolidation not bearing capacity failure). The calculation of 2 Cv ¼ the coefficient of consolidation (m /s) stress and strain distributions during and after H ¼ the length of the drainage path (m) yield requires the use of numerical models, such as finite element analysis. On occasions, the Soil-like materials that have been unloaded to inelastic component can be significantly higher some degree with the passage of geological time than the elastic component (Vasundhara, 1999). are referred to as being over-consolidated. A general formula for elastic settlement, Se,is Unloading results in an increase in the volume given by Eq. A4.4 which, when applied to a coal of these materials, referred to as either rebound pillar, translates into Eq. A4.5. The influence or negative consolidation. factor, Ip, depends on Poisson’s ratio, the ratio In coal mining environments, the undrained and of the thickness of the foundation layer, t, to the drained moduli of soil-like foundation materials width of the footing, w, and the shape of the such as underclay and degraded claystone can be footing. A number of theoretical solutions have one to two orders of magnitude lower than those of been developed for elastic settlement, giving rise the surrounding strata. Hence, settlement of this to a range of influence factors. material can result in significant roof to floor con- qBIp vergence, leading to elevated levels of surface sub- Se ¼ ðA4:4Þ sidence which have sometimes been misinterpreted Eu as indicating an unstable pillar system. where

Se ¼ elastic settlement (m) Settlement B ¼ footing diameter or width (m) q ¼ footing working stress (Pa) ¼ Three components contribute to the settlement of Eu undrained modulus (Pa) ¼ soil-like strata above and below a coal pillar, Ip a dimensionless inﬂuence factor, which is a namely: function of footing ﬂexibility, footing width, footing length, thickness of foundation layer ’ • immediate settlement, or undrained settle- and Poisson s ratio ment, due to deformation of the microstruc- ture of the foundation material without a σ ¼ ipswminIp ð : Þ change in its volume; Se A4 5 Eu • primary consolidation settlement, resulting from dissipation of pore water pressure as the where foundation material moves from an undrained to a drained state; and σips ¼ induced average pillar stress (Pa) • secondary consolidation settlement, due to ¼ average pillar stress minus vertical deformation under the effects of constant component of primitive stress effective stress and often referred to as creep. wmin ¼ minimum pillar width (m)

Immediate settlement is also referred to as Long term settlement, or primary consolida- elastic settlement, although it can include an tion, is a function of the compressibility of the 582 Appendix 4: Foundation Behaviour

material being loaded and its existing state of T1 ¼ time when secondary consolidation is compaction, both of which are dependent on the assumed to begin (s) stress history of the material. Equation A4.6 T2 ¼ time for which secondary settlement is defines the general solution for settlement of calculated (s) normally consolidated material as given by Das (1998). σ þ Δσ vivi Bearing Capacity Cct ve vi Sp ¼ log ðA4:6Þ 1 þ eo σve Bearing capacity theory is premised on the where assumption that upon exceeding a certain stress condition, rupture surfaces will develop in the ¼ Sp primary consolidation settlement (m) foundation material and it will fail in shear. In ¼ Cc compressibility index situations where the foundation material is t ¼ foundation layer thickness (m) homogenous over a thickness of two to three ¼ eo void ratio (a measure of the existing state of times the width of the footing, failure is generally compaction) considered to take one of three progressive σ ¼ 2 ve vertical effective stress (N/m ) forms: 2 Δσvi ¼ induced vertical stress (N/m ) • Punch shear failure Many highly over-consolidated materials • Local shear failure behave approximately as linear elastic materials • General shear failure within the working stress ranges encountered in civil engineering practice. Therefore, Eq. A4.4 is Punch shear failure occurs when compression often extended to these situations by substituting of the foundation material is sufficient to cause a drained value for modulus and selecting influ- shear failure surfaces to develop beneath the ence functions based on the value of Poisson’s footing. These delineate a wedge of material, ratio for the drained state. Some procedures corresponding to Zone 1 in Fig. A4.2, that is incorporate additional and/or alternative influ- then driven into the ground, resulting in compac- ence functions. tion. There may be little movement of the ground Secondary consolidation involves the ongo- on the sides of the footing and no visible signs of ing readjustment of material particles under failure. This behaviour is more likely to occur in sustained load. The amount of secondary settle- very compressible materials such as loose sands ment,Ss, that occurs over time is directly pro- and weak clays. portional to the thickness of the foundation layer Local shear failure is an extension of punch after primary consolidation and its secondary shear failure in which compression of the compression index,Cα, with this relationship given by Eq. A4.7. T1 Ss ¼ Cαt100log ðA4:7Þ T2 where

Ss ¼ secondary consolidation settlement (m) Cα ¼ secondary compression index t100 ¼ foundation layer thickness at end of primary consolidation (m) Fig. A4.2 Bearing capacity shear rupture zones Appendix 4: Foundation Behaviour 583

Fig. A4.3 Bearing capacity failure beneath abutment Fig. A4.4 Extrusion of foundation material from beneath pillars in partial pillar extraction workings, resulting in a pillar as evidenced by the angle of the props and the some 2 m of closure in 2.7 m high workings condition of the pillar side foundation material leads to the formation of slip the pillar because the tensile strength of the pillar failure surfaces outside of the perimeter of the is minimal, especially in the presence of cleating. footing. These correspond to Zone 2 in The pillar failure mode moves from one of com- Fig. A4.2. The shear failure surfaces do not day- pressive failure under axial load to one of tensile light, although the surface around the footing may failure under lateral stress. In these bulge slightly. circumstances, the distinction between extrusive General shear failure is the most common foundation failure and pillar system failure type of shear failure and is characterised by associated with low cohesion and friction well-defined slip surfaces that extend from one interfaces becomes blurred as both mechanisms edge of the footing and daylight on the opposite are likely to be active and interacting. side of the footing (Fig. A4.2). Materials that are In thick foundation situations (t > 2w, where practically incompressible and have finite shear w is the width of the footing), it is generally strength fail in general shear. As the material in accepted that more rigid and incompressible Zone I moves down, plastic flow is initiated in foundation materials will fail in general shear, Zone II. The overlying material in Zone III whilst more compressible materials will fail in provides resistance to this displacement but local shear or punching shear. A foundation once this is overcome, the shear failure planes comprising saturated, normally consolidated extend to the surface and the material around the clay will fail in general shear if it is loaded so footing bulges. Figure A4.3 shows an example of quickly that there is no time for volume change general shear failure of the floor adjacent to to take place, whilst it may fail in punching pillars in a coal mine in the Lake Macquarie shear if the loading rate is sufficiently slow region of NSW, Australia. that the material has time to drain and compress If the thickness, t, of a weak foundation layer (Vesic 1975). is limited or the layer is significantly weaker than Evaluation of ultimate bearing capacity is adjacent low strength layers, slip surfaces may usually concerned with general shear failure. not develop throughout the full thickness of the Bearing capacity formulae date back to the mid foundation. Rather, the layer can fail, shear on 1850s, with a major advance made when Prandtl bedding planes and extrude laterally from under (1921) adapted limit equilibrium solutions (or over) the footing such as in the field case derived for the penetration of soft, homogenous, illustrated in Fig. A4.4. When this occurs in isotropic, rigid materials by hard metal punches coal mining situations, the pillar is subjected to to assess the bearing capacity of shallow lateral tension and open cracks can develop from foundations. Buisman (1940) developed this for- roof to floor and extend through the full width of mulation into the Buisman-Terzaghi bearing 584 Appendix 4: Foundation Behaviour

ÀÁ capacity equation (Terzaghi 1943) for a uni- Nγ ¼ 1:5 Nq À 1 Tanϕ Brinch À HansenðÞ1970 formly loaded, infinitely long strip footing ðA4:12Þ founded on a homogenous incompressible mate- ÀÁ rial (Eq. A4.8). Subsequently, this equation has Nγ ¼ 2 Nq þ 1 Tan ϕ Vesic ðÞ1975 been modified to form the basis of a myriad of ðA4:13Þ bearing capacity formulae. ÀÁ π ϕ γwNγ ¼ þ φ þ q ¼ cN þ γdN þ ðA4:8Þ Nγ 2 Nq 1 Tan Tan u c q 2 4 5 Chen and McCarronðÞ1990 ðA4:14Þ where Equation A4.12 was developed for cohesive, qu ¼ ultimate bearing capacity frictional material such as soft rock and over- Nc, Nq, Nγ ¼ bearing capacity factors which consolidated clays and has been adopted by depend on the value of internal friction, ϕ Bieniawski (1987) and Brady and Brown (2006) w ¼ width of footing for mine design. Experimental results suggest γ ¼ unit weight of soil that it produces lower end values in comparison d ¼ depth of footing beneath the surface to other expressions for Nγ (Chen and McCarron 1990). Equation A4.8 is made up of three Equation A4.8 assumes the strip footing to be components representing: infinitely long and, as such, it is a two-dimensional solution. According to Vesic • cohesion of the foundation material (‘c’); (1975), a footing can only be assumed to be an • surcharge load acting on the surrounds of the infinite strip in a strict sense once its length, L, is footing (‘γd’); and greater than 10 times its width, w; practically, • unit weight of the foundation material (‘γ’). however, this can be assumed once L/w > 5. For smaller L/w ratios, semi-empirical shape correc- A range of mathematical relationships has been tion factors have to be introduced and so proposed for determining Nc,Nq,andNγ,allof Eq. A4.8 translates to Eq. A4.15. which are a function of ϕ. The variation in values γ ¼ þ γ þ wNγSγ ð : Þ for Nc and Nq is relatively minor, with the values qu cNcSc dNqSq A4 15 given by Eqs. A4.9 and A4.10 finding extensive 2 application (e.g. Vesic 1975; Smith 1990; Brady where and Brown 1993; Craig 1997). ¼ π ϕ Sc, Sq, Sγ dimensionless shape factors N ¼ Tan2 þ eπ tan ϕ ðA4:9Þ q 4 2 The shape factors recommended by Vesic ÀÁ (1975) for rectangular, circular and square Nc ¼ Nq À 1 Cotϕ ðA4:10Þ footings are presented in Table A4.1. They are There is around a seven fold range in the values proposed for Nγ, associated mainly with the manner in which a representative value of ϕ is Table A4.1 Bearing capacity shape factors (after Vesic, 1975) selected (Vesic 1975). Equations A4.11, A4.12, A4.13, and A4.14 define four expressions which Shape Sc Sq Sγ find wider use. Strip 1.0 1.0ÀÁ 1.0 ÀÁ ÀÁ L L Rectangular L Nq þ ϕ À : ÀÁ 1 þ 1 w tan 1 0 4 w ¼ À ðÞ: ϕ ðÞ w Nc Nγ Nq 1 Tan 1 4 Meyerhof 1963 þ ϕ Circular and 1 þ Nq 1 tan 0.60 ðA4:11Þ square Nc Appendix 4: Foundation Behaviour 585

Table A4.2 Bearing capacity shape factors (after on added signiﬁcance in an underground mine Terzaghi 1943) setting include:

Shape Sc Sq Sγ Strip 1ÀÁ 1 1 ÀÁ • Interaction between footings: In civil engineer- Rectangular þ : L 1 À : L 1 0 2 w 1 0 2 w ing applications, the spacing between footings Square 1.2 1 0.8 is often many times greater than the width of Circular 1.2 1 0.6 the footings. The converse applies in most underground coal mining environments, giving rise to the potential for pillar foundations to not unique, with those recommended earlier by interact. The confinement provided by a pillar Terzaghi (1943) and shown in Table A4.2 also to the foundation zone of an adjacent pillar continuing to find wide acceptance. could be expected to retard the development Several techniques have been proposed for of shear failure, resulting in an increase in bear- estimating the ultimate bearing capacity of ing capacity. Benefits are difficult to quantify in non-homogenous and anisotropic foundation the field but laboratory studies of strip footings materials. These include: by Stuart (1962) and West and Stuart (1965) revealed that bearing capacity started to • Mandel and Salencon (1969) – a weak increase because of interaction once the dis- deformable layer overlying a layer of infinite tance between footings was less than 3 times rigidity and strength; the footing width. Bearing capacity peaked at • Brown and Meyerhof (1969) and Vesic (1973) 200 % of that for a single footing when the – a cohesive two layer model, with undrained spacing between the footings was reduced to ϕ ¼ conditions in both layers ( 0); 0.25 times the footing width. • Smith (1990) – a procedure for averaging • Discontinuities: Discontinuities in the founda- cohesion and friction values in thin soil layer tion material reduce the shear strength of the situations; material mass. Usually, it is not feasible to • Chugh et al. (1990) – a shallow foundation on determine the in situ shear strength of frac- a two layered rock system with consideration tured material from laboratory determined of cohesion and friction in each layer. values of cohesion and friction. Operational strength can be expected to lie somewhere Irrespective of which bearing capacity proce- between laboratory determined shear strength dure is invoked, the bearing capacity of a surface and the shear strength of the fracture planes. ¼ foundation (depth of footing, d, 0) is least Ganow (1975) used a reduction value of 35 % when it is fully saturated and in an undrained for studies in the Illinois coal basin. The ϕ ¼ ¼ state, in which case 0 and Nγ 0. In a author also applied a reduction factor of mining environment in which the roadways 60 % to account for laboratory testing being have not been backfilled, flooded or affected by biased towards stronger, less fractured roof falls, the surcharge load of any material samples as a result of weak material not sur- around the pillar can also be equated to zero; viving the specimen preparation process. ¼ that is, q 0. Hence, Eq. A4.15 reduces to one • Groundwater and flooding: Water can affect term, defined by Eq. A4.16. all three components of bearing capacity. The ¼ ð : Þ cNc component is affected because the shear qu cNcSc A4 16 strength of soft and weak rock and soil The more common formulae which have been materials can be reduced significantly in the applied to mining environments on the basis presence of water. For example, the uncon- that ϕ ¼ 0 are summarised in Table A4.3. fined compressive strength of selected, wet, Some of the assumptions and approximations coal-bed floor strata has been found to be only associated with bearing capacity models that take 26 to 40 % of that in its dry state (Bieniawski 586 Appendix 4: Foundation Behaviour

Table A4.3 A selection of bearing capacity formulae which have found application in underground coal mining for the case of f ¼ 0

Theory Pillar shape Ultimate bearing capacity (qu) Modiﬁcation factors

Classical: Strip cNc ¼ 5:14cNc ¼ 2 þ π ¼ 5:14 (Buisman-Terzaghi) Single homogenous layer

Classical: incorporating shape cNcSc factors hi Single homogenous layer Square Nq Nc ¼ 5:14 cNc 1 þ ¼ 6:168c Nc N q ¼ 0:2 Rectangular L Nq Nc cNc 1 þ w Nc L ¼ c 5:14 þ 1:028 w

Mandel and Salencon (1969) Strip cNcFc ¼ 5:14cFc Nc ¼ 5:14

Soft layer over a layer of infinite w/t Fc rigidity and strength 1.41 1 2 1.02 3 1.11 4 1.21 5 1.30 6 1.4 8 1.59 10 1.78 Thereafter: NcFc (π + 1 + 0.5 w/t) Brown and Meyerhof (1969) cNm where Nm is a functionhi of c2/c1 Soft layer overlying a stiffer layer Strip : þ : w w > : c1 4 14 1 1 t fort 0 9 c1,t1 ¼ cohesion and thickness of 1 1 top layer hi c2,t2 ¼ cohesion and thickness of Square w w Derived for a circular ffi c1 5:05 þ 0:66 for > 1:5 bottom layer t1 t1 footing of diameter ÀÁ w. t1 Stiffer layer overlying a softer layer Strip 1:5 c1 þ 5:14c2 ¼ w ÀÁ c1,t1 cohesion and thickness of Square ffi : t1 þ : Derived for a circular 3 0 w c1 6 05c2 top layer footing of diameter c2,t2 ¼ cohesion and thickness of w. bottom layer

1987). If the foundation material is saturated the design stage. One consequence of mine but the water table is more than a distance of workings becoming ﬂooded is that a sur- twice the footing width (i.e. >2w) below the charge load is applied to the roof and ﬂoor

footing, the γqNq component can be based on surfaces of the foundations, in which case the the unit weight, γ, of the foundation material. γwNγ component may need to be included in Otherwise, this component should be based on bearing capacity calculations. effective material weight, γ´, in order to • Scale effects on strength: Bearing capacity account for buoyancy effects. Such effects theory does not account for reduced average may be inevitable when mine workings ﬂood shear strength along failure slip planes as and, therefore, need to be taken into account at foundation size increases. Appendix 4: Foundation Behaviour 587

Creep expansion of clay minerals in the presence of water. Montmorillonite is the most active of In underground coal mining, the term creep is these minerals, increasing in volume by as used to describe a regional, time dependent fail- much as 300 %. Research by Li et al. (2001) ure of the pillar system that results in severe seam suggests that the roof and floor material immedi- convergence, roof and floor failure, rib spall and ately above and beneath a pillar are not prone to in some instances, total collapse. In classical this behaviour because confinement prevents the engineering, it refers more specifically to the ingress of moisture and resists swelling. How- process of continued deformation (strain) of a ever, material that is unconfined in an adjacent material under sustained constant load. roadway may undergo substantial swelling. It is Classical engineering creep is a function of often difficult to distinguish the contribution that deviator stress (σ1–σ3). Most soft and weak rocks swelling makes to the overall uplift, or heave,of exhibit both immediate (elastic) and delayed coal mine floor strata. (viscous) deformation when subjected to load (Fig. A4.5). Immediate elastic strain is followed by a period of primary creep which develops at a Underground Experience decreasing rate. This may be followed by second- with Applying Classical Bearing ary creep that occurs at a near constant rate. If a Capacity Principles material is already approaching its peak strength, secondary creep may develop into tertiary creep, Experience to date in applying classical settle- in which case strain increases exponentially with ment and bearing capacity principles and design time until failure occurs. concepts to coal mining environments has demonstrated that there is significant uncertainty associated with these civil engineering approaches. A considerable amount of this expe- Swell rience derives from mining in Illinois in the USA and in the Lake Macquarie region of NSW, In solid mechanics, the terms swell and rebound Australia. In the latter case, there has been a are synonymous and refer to negative consolida- particular focus on the behaviour of the Awaba tion when a material is unloaded. In underground Tuff floor strata of the Great Northern Seam. ‘ ’ coal mining, the term swell is ascribed a similar This material is generically referred to as meaning in that it generally refers to the uplift of ‘claystone’ but mapping has shown it to be very the immediate floor associated with the variable in composition, thickness and strength, both vertically and laterally. It can comprise dis- tinct layers of clay, shale, tuff, chert, sandstone and conglomerate to give a range in UCS from less than 0.5 MPa to well in excess of 40 MPa. Some tuffaceous layers have the potential to undergo a transition over time from a moderately hard rock to a saturated soil. Table A4.4 summarises predicted versus measured outcomes as the result of applying settlement theory in partial pillar extraction panels in the Great Northern Seam at one mine (Mine A). The elastic settlement predictions were based on Eq. A4.5. The material was considered by the consultant to behave as an over- Fig. A4.5 Stages of creep behaviour in rock consolidated clay and so predictions of primary 588 Appendix 4: Foundation Behaviour

Table A4.4 Predicted versus measured elastic and primary settlement of claystone floor (Awaba Tuff) at a NSW mine. Predicted Elastic Primary consolidation Mining panel settlement (mm) settlement (mm) Measured settlement (mm) South P 14 80 13 mm after 4 months and continuing South J 24 118 17 mm after 2.5 years and possibly stabilising South M 18 66 6 mm after 3 months, then stable South O 29 111 5 mm after 9 months South West A1 25 86 17 mm after 12 months consolidation were also based on Eq. A4.5 using the consequences of failure would be severe. estimates of drained modulus. Application of bearing capacity formulae by Vasundhara et al. (1997) evaluated this pre- Ganow (1975) to the back analysis of floor dictive approach in a neighbouring mine (Mine heave in the coal mines of Illinois led to the B) where the Awaba Tuff was around 10 m thick conclusion that failure was occurring at a safety and loaded by coal pillars that were 22 m wide by factor of almost 7. Seedsman and Gordon (1992a) 29 m long. The material was treated as a nor- calculated a safety factor of 9.1 when the bearing mally consolidated clay with predictions being capacity formula of Mandel and Salencon (1969) based on Eq. A4.6. Primary consolidation settle- for infinitely long pillars was applied to rectangu- ment of 1.7 m was predicted, which far exceeded lar and square pillars in the Great Northern Seam measured surface subsidence over similar mine at Cooranbong Colliery. They concluded that this workings. As at day 836, the measured consoli- implied cohesion had to be 1/8 of the average dation ranged from 30 mm to 140 mm, laboratory value quoted by Seedsman and Mallet corresponding more closely to the outcomes at (1988a) and 1/13 of the value measured at the site. Mine A where analysis was based on only a 1 m Further application of the Mandel and thickness of material (Table A4.4). At both mine Salencon (1969) formula by Seedsman and sites, the measured rate of consolidation differed Gordon (1992a) to rectangular pillars of markedly from the theoretical rate. L/w ¼ 3.5 in the Great Northern Seam at It is well known from civil engineering foun- Cooranbong Colliery and L/w ¼ 3.2 in the dation practice that consolidation settlement Fassifern Seam at Wyee Colliery produced safety estimates using consolidation test data directly factors of the order of 5 and 15, respectively. can grossly over-estimate settlement for over- These safety factors were based on the most consolidated clays. The greater the over- critical stability state of ϕ ¼ 0. Seedsman and consolidation, the greater the error in predictions. Gordon proposed an alternative model of bearing This comes about because of the effect of the capacity failure as a means of avoiding unrealis- vertical applied load on pore water pressures tic reductions in material properties whilst still when there is lateral yield (Skempton and employing classical bearing capacity formulae. Bjerrum 1957). Hence, it might be expected This model was based on a number of that if applied to rock-like materials, Eq. A4.5 assumptions, including that bearing capacity fail- would result in a gross over-estimation of con- ure only occurred beneath the outer 1.5 to 2 m rib solidation settlement, as appears may have been zone of a pillar. However, the model could not the situation in these case studies. account for behaviour at Wyee Colliery. In civil engineering, it is common practice to Mills and Gale (1993) and Mills and Edwards apply a safety factor of around 2 to bearing capac- (1997) studied 25 sites, of which 19 were located ity design, increasing to 3 where additional uncer- in the Great Northern Seam and five in the tainty exists in the adequacy and reliability of field overlying Wallarah Seam in the Lake Macquarie data or the bearing capacity formulae, or where region, with the other site being in Illinois, USA. Appendix 4: Foundation Behaviour 589

Significant surface subsidence had occurred at drained modulus for Awaba Tuff. Seedsman 16 of these sites, many of which comprised a and Gordon (1992b) correlated uniaxial com- partial extraction layout whereby every alternate pressive strength and elastic modulus to moisture row of pillars had been extracted. Mills and Gale content. A Æ50 % error band was associated with (1993) reported that bearing capacity theory these correlations. Chugh and Pytel (1992) based predicted failure loads that were four to five estimates of the ultimate bearing capacity and times greater than those at which these pillar deformation modulus of weak floor strata systems typically failed. In order to produce bear- beneath a full size pillar on the results of bearing ing capacity failure loads that corresponded tests conducted with plates up to 0.6 m in diame- with pillar loads, the researchers had to equate ter. The area of influence of plates of this size is the properties of the claystone floor to a fully very limited in comparison to the area of influ- saturated clay in an undrained state (ϕ ¼ 0). ence of a pillar footing. They expressed the view that it was difficult Seedsman (2008, 2012) reported on the appar- to conceive claystone having a friction angle ent successful application of the Mandel and even as low as 20 and that it was their belief Salencon bearing capacity formula to the design that the claystone material under the pillars of partial extraction pillar systems at Awaba Col- retained essentially rock-like properties. The liery in NSW, a mine with a history of pillar investigators went on to conclude that a classical foundation failure under stiff superincumbent bearing mechanism was not appropriate to strata. In 2014, however, surface subsidence in explain the field behaviour, albeit that claystone excess of one metre was detected over a portion behaviour was still involved in the pillar failure of these workings. mechanism. The variety of assumptions and modifications Assuming that classical settlement theory is associated with applying classical bearing capac- applicable to Awaba Tuff in at least some ity theory to underground coal environments and circumstances, a range in laboratory derived the range and accuracy of outcomes give rise to values of 0.1 to 4.0 m2/year for the consolidation considerable uncertainty about the reliability of index of this material translates to a 40 fold range this approach. Most formulae are premised on in predictions of the time that it will undergo laboratory scale testing, empirical models, and consolidation. Inaccuracies in drainage path elastic and plastic theory concerned with the length can be more critical because outcomes behaviour of soils, sands and clays assumed to are proportional to the square of this factor. For be homogeneous to a depth of two to three times the same circumstances, one investigator the width of the footing. Similar conditions rarely assumed drainage path length to be half the exist in underground coal mining environments. joint spacing in the claystone, whilst another Therefore, application of bearing capacity assumed it to be half the thickness of the formulae to foundation design in underground claystone bed. This translated to a 2500 fold coal mining warrants careful risk assessment difference in calculated consolidation time. A with consideration being given, in particular but lack of data required Vasundhara (1999) to not exclusively, to the following factors: assume London Clay values for the compressibility index, Cc, and void ratio, eo, of Awaba Tuff • The validity and accuracy of the formulae. when calculating the primary consolidation set- There is a range of formulae and a variety of tlement noted earlier. empirically derived bearing capacity factors. A A range of approximate methods have had to range of values for shape factors has also been be applied to address the practicalities of deter- proposed in an attempt to adapt the mining material properties in a mining environ- two-dimensional solutions to three- ment. Seedsman (2008) and Seedsman and dimensional circumstances. Laboratory scale Mallet (1988b) suggested a 50 % reduction in studies involving sand and clay-like materials laboratory measured values of undrained and have featured strongly in the derivation of 590 Appendix 4: Foundation Behaviour

these factors and in formulae which address • Load scale. The loads to which pillar two layer situations. Each of these factors is a foundations are subjected are typically at source of error in its own right. An arguably least one order of magnitude greater than greater source of error arises when attempting those encountered in civil engineering. to apply bearing capacity formulae to a mine • Interaction between footings. The footing environment, since the formulae are tailored to width to spacing ratio in a mining environment reasonably homogenous foundation materials is inverse to that in a civil engineering environ- and do not take account of variable material ment, thereby giving rise to a much greater properties and defects, such as fractures and potential for interaction between footings. joints, inherent in coal pillar foundations. • Footing construction. Pillar footings comprise • Material properties. It is well established in natural, non-reinforced material that is civil engineering practice that settlement and embedded with vertical and horizontal defects bearing capacity calculations are quite sensi- (joints, cleat, bedding planes) and is of mini- tive to the accuracy of input data and the mal tensile strength. Conversely, civil engi- reliable determination of the required material neering footings are usually constructed of properties. There are serious practical, tech- quality controlled, reinforced materials of nological and financial limitations to sourcing higher tensile and compressive strength. appropriate, adequate and reliable data from • Time. Rock mass properties can change over underground coal mine environments, espe- time in a mine environment, especially upon cially prior to mining having taken place. being exposed to moisture or sustained load. • Dimensional scale. The width of a pillar foot- • Flooding. Flooding of mine workings in time ing can be an order of magnitude or more to come can have implications for, firstly, the greater than typical civil engineering footings selection of appropriate bearing capacity and, therefore, the zone of influence of the formulae at the design stage and, secondly, footing extends for a greater distance into the range of material properties that the design the foundation. Consideration has to be procedure has to cater for over the required given to whether the material within this period of pillar system stability. zone of influence is homogenous and, therefore, whether it is valid to apply bearing Unfortunately, it is a matter of fact that many capacity formulae in the given circumstances. of these factors cannot be adequately quantified, • Multiple layered situations. The wider footing irrespective of which approach is adopted to and higher loading regime encountered in foundation design. mining extends the zone of influence of the footing, thereby increasing the likelihood that foundation response will be affected by Conclusions the behaviour of multiple layers of strata. It is likely that these multiple layers will There have been a number of instances in NSW contain a variety of materials, some with where elevated surface subsidence is very likely contrasting mechanical properties. Classical attributable to some form of classical bearing bearing capacity formulae do not explicitly capacity failure of the pillar foundation and/or account for these situations, although some lateral plastic flow of material from beneath the formulae may find application to specific pillars resulting in a change in the behaviour circumstances. Implicit approaches, such as mode of the pillars. Induced tensile failure is calculating effective material properties of not as likely to arise in civil engineering footings a number of layers and inputting these because there is a degree of control over site values into classical bearing capacity selection and footing design, including reinforce- formulae, can fail to give proper consideration ment against tensile failure. to specific layers modifying or controlling Circumstances where very high safety factors behaviour. need to be applied or material input properties Appendix 4: Foundation Behaviour 591 severely modified in order to achieve bearing rate of load transfer to the panel pillars, thereby capacity predictions that are consistent with field providing time for the foundation material to drain performance suggest that the foundation and for friction angle to recover. In the worst case, behaviour mechanism or formula may not have interpanel pillars can prevent or retard the failure been appropriately chosen; that this mechanism progressing through the mine. It is noteworthy that had deficiencies when applied to the particular a significant number of failures attributed to floor mining environment; and/or that input material bearing capacity in Australia have been associated properties may not be representative of field with reducing the size of panel and interpanel properties. It is possible that on occasions, pillar pillars and with removing interpanel pillars. foundation failure may have been the outcome of Against this background, the process of settle- several interactive mechanisms, one of which may ment and bearing strength is still not fully under- have involved classical foundation behaviour. stood and there may be other mechanisms There is little doubt that some pillar system involved that have yet to be identified or properly instabilities attributed to foundation failure would appreciated. Making design distinctions between not have developed if the pillars had not been foundation failure mechanisms and accounting undersized for the function required of them and, for how interaction between coal pillar footings therefore, overstressed in the first instance. It is and foundation layers impacts on failure also likely that some floor heave events associated mechanisms is surrounded with uncertainty and with other mechanisms, such as swelling clay warrants the assistance of numerical modelling. minerals or buckling failure of stiff beds in the If civil engineering settlement and bearing floor, have been misconstrued as plastic flow and capacity formulations are to be persevered with, therefore, as classical bearing capacity failures. it could be judicious to utilise numerical Quantifying the type of foundation behaviour modelling to identify possible failure mechanisms operating in some mining mechanisms and to undertake parametric and environments is complicated further by the factor sensitivity studies to assess the vulnerability of of time. The various bearing capacity formulae design outcomes to uncertainties in input data presented in Table A4.3 represent the worst-case and failure models. situation of an undrained foundation, where ϕ ¼ 0. Under normal circumstances, it is difficult to conceive the friction angle of most coal mine strata, including claystone, being less than References 10. Pillar load builds up over a period of time as Bieniawski, Z. T. (1987). Strata control in mineral engi- the mining face is advanced, thereby providing neering. Rotterdam: A.A. Balkema. time for some of the excess pore water pressure Brady, B. H. G., & Brown, E. T. (1993). Rock mechanics to be dissipated and for a partial recovery in for underground mining (2nd ed.). London: Chapman & friction angle. However, there is one circum- Hall. stance which could give rise to friction angle Brady, B. H. G., & Brown, E. T. (2006). Rock mechanics for underground mining (3rd ed.). Dordrecht: Springer. being reduced to a very low value over an exten- Brinch-Hansen, J. (1970). A revised and extended for- sive area. This might occur when stiff, strong mula for bearing capacity. Danish Geotechnical Insti- superincumbent strata fails and subsides over a tute Bulletin, 28, 5–11. very short time period so as to result in a regional Brown, J. D., & Meyerhof, G. G. (1969). Experimental study of bearing capacity. Paper presented at the 7th step increase in pillar load. international conference on soil mechanics & founda- Substantial interpanel pillars are one potential tion engineering, Mexico, 45-61. Sociedad Mexicana control measure for this hazard. They can be de Mecanica. designed to limit panel span to prevent the stiff- Buisman, A. S. K. (1940). Grondmechanica. Delft: Waltman. Chen, W. F., & McCarron, W. O. (1990). Chapter 4. ness of the superincumbent strata reducing to zero In Foundation engineering handbook. New York: so that the panel pillars are not exposed to a rapid Chapman & Hall. regional increase in load. They can also slow the 592 Appendix 4: Foundation Behaviour

Chugh, Y. P., Pula, O., & Pytel, W. M. (1990). Ultimate settlement. Paper presented at the 11th international bearing capacity and settlement of coal pillar conference ground control in mining, Wollongong. sub-strata. International Journal of Mining and Uni. Wollongong. Geological Engineering, 8, 111–130. Seedsman, R. W. (2008). Awaba – Understanding soft Chugh, Y. P., & Pytel, W. M. (1992). Design of partial floors and massive conglomerates. Paper presented at extraction coal mine layouts for weak floor strata the general meeting of Mine Managers Association of conditions. Paper presented at the workshop on coal Australia. MMAA. pillar mechanics and design, Santa Fe, NM, 32-49. Seedsman, R. W. (2012). The strength of the pillar-floor USBM. system (pp. 23–30). Paper presented at the Coal 2012: Craig, R. F. (1997). Soil mechanics (6th ed.). London: Coal operators’ conf., Wollongong. Illawarra Branch Chapman and Hill. AusIMM. Das, B. M. (1998). Principles of geotechnical engineering Seedsman, R. W., & Mallet, C. W. (1988a). Claystones of (4th ed.). Boston: PWS Publishing Company. the Newcastle coal measures (p. 84). D. P. I. a. Ganow, H. C. (1975). A geotechnical study of the squeeze Energy, Trans., NERDDP Project 902, end of grant problems associated with the underground mining of coal. report no. 0749. Canberra: Nat. Energy Research PhD thesis, University of Illinois, Champaign, IL. Development & Demonstration Council (NERDDC), Li, G., Vasundhara, V., Brynes, R., Turner, J., Aust. Federal Government. Hebblewhite, B. K., & Whitley, R. (2001). Investiga- Seedsman, R. W., & Mallet, C. W. (1988b). Claystones of tion of long term stability of mine workings on the Newcastle Coal Measures. Canberra: NERDDC. claystone floor and associated subsidence issues (pp. Smith, G. (1990). Elements of soil mechanics (6th ed.). 25–36). Paper presented at the 5th triennial conference Oxford: BSP Professional Books. Mine Subsidence Technological Society, Maitland, Stuart, J. G. (1962). Interference between foundations NSW. with special reference to surface footings on sand. Mandel, J., & Salencon, J. (1969). Force Portante D’Un Geotechnique, 12(1), 15–22. Sol Sur Une Assise Rigide. Paper presented at the 7th Terzaghi, K. (1943). Theoretical soil mechanics. New international conference on soil mechanics and foun- York: Wiley. dation engineering, Mexico, 157-164. Sociedad Vasundhara, V. (1999). Geomechanical behaviour of soft Mexicana de Mecanica. floor strata in underground coal mines (Vols. 1 and 2, Meyerhof, G. G. (1963). Some recent research on the p. 586). ACARP end of grant report C4026. Brisbane: bearing capacity of foundations. Canadian Geotechni- Australian Coal Association Research Program cal Journal, 1(1), 16–26. (ACARP). Mills, K. W., & Edwards, J. L. (1997). Review of pillar Vasundhara, V., Hebblewhite, B. K., & Galvin, J. M. stability in claystone floor strata. Paper presented at (1997). Engineered mine design in soft strata the symposium on safety in mines: The role of geol- environments, Research report RR 4/97. Sydney: ogy, Sydney, 161-168. University of New South School of Mining Engineering, University of New Wales. South Wales. Mills, K. W., & Gale, W. J. (1993). Review of pillar Vesic, A. S. (1973). Analysis of ultimate loads of shallow behaviour in claystone strata (Consulting report). foundations. Journal of the Soil Mechanics and Report to Elcom Collieries and Coal and Allied. Foundations Division, 99(SM1), 575–577. Prandtl, L. (1921). Uber die Eindringungsfestigkeit Vesic, A. S. (1975). Bearing capacity of shallow Plastischer Baustoffe und die Festigkeit von foundations. In H. F. Winterkorn & H. Y. Fang Schneuten. Z. fur Angewandte Mathematik und (Eds.), Foundation engineering handbook (Vol. 3, Mechanik, 1(1). pp. 121–147). New York: Van Nostrand Reinhold. Seedsman, R., & Gordon, N. (1992a). Weak claystone West, J. M., & Stuart, J. G. (1965). Oblique floors and their implications to pillar design and set- loading resulting from interference between surface tlement (pp. 548–555). Paper presented at the 11th footing on sand (pp. 214–217). Paper presented at the international conference ground control in mining, 6th international conference on soil mechanics & Wollongong, Australia. AusIMM. foundation engineering, Montreal. Seedsman, R. W., & Gordon, N. (1992b). Weak claystone floors and their implications to pillar design and Appendix 5: Formulae for Calculating Load on a Pillar Based on Abutment Angle Concept for the Most General Case

The formulations are based on the general case of parallelepiped pillars as deﬁned in Fig. A5.1.

Fig. A5.1 Geometry associated with a layout of parallelepiped pillars

Parallelepiped Pillars – Depth, H 0.5 W Tan(β)

# Springer International Publishing Switzerland 2016 593 J.M. Galvin, Ground Engineering - Principles and Practices for Underground Coal Mining, DOI 10.1007/978-3-319-25005-2 594 Appendix 5: Formulae for Calculating Load on a Pillar Based on Abutment Angle Concept...

b W W2 Tan ðÞβ b 0:025 Hw þ 1 þ À w þ 2 min 2 2 8 2 Sin ðÞθ σaps ¼ ðÞMPa ðA5:1Þ wmin w2 where:

wmin ¼ w1 Sin ðÞθ

Parallelepiped Pillars – Depth, H < 0.5 W Tan(β)

b H b 0:025Hw þ 1 þ w þ 2 min 2 2Tan ðÞβ 2 Sin ðÞθ σaps ¼ ðÞMPa ðA5:2Þ wmin w2

where wmin ¼ w1 Sin(θ) b1 ¼ bord width normal to goaf edge ¼ gateroad w1 ¼ pillar dimension parallel to cut‐through width w2 ¼ pillar dimension parallel to goaf edge b2 ¼ bord width normal to cut‐through direction θ ¼ smaller internal angle between pillar sides W ¼ excavation span À rib to rib (θ 90 ) Appendix 6: Timber Prop Performance Parameters

Introduction where

Speciﬁcations and recommendations for timber P ¼ load bearingcapacityðÞ tonnes props vary with species and from country to L ¼ proplengthðÞ mm country. A number of these are provided as d ¼ propdiameterðÞ mm points of reference.

Australia South Africa

According to Menzies (c1970), Australian under- Figure A6.1 shows the load performance of ground coal mining experience has shown that as a 100 mm and 150 mm diameter wattle and saligna general rule, the diameter of a eucalypt hardwood timber props plotted as a function of prop length. prop should be one inch (25.4 mm) for every foot (0.3054 m) length of prop. This generates the metric prop dimensions presented in Table A6.1. Shepherd and Lewandowski (1994) proposed that the strength of an Australian eucalyptus (hardwood) prop is given by: L P ¼ 54:42 À 1:17 ðA6:1Þ d

Table A6.1 Australian hardwood prop dimensions based on recommendations of Menzies (c1970) Hardwood prop Suggested prop length (m) diameter (mm) 2 166 2.5 208 3 250 3.5 291 Fig. A6.1 Strength properties of wattle and saligna tim- 4 332 ber props (Adapted from Wagner 1994)

# Springer International Publishing Switzerland 2016 595 J.M. Galvin, Ground Engineering - Principles and Practices for Underground Coal Mining, DOI 10.1007/978-3-319-25005-2 596 Appendix 6: Timber Prop Performance Parameters

Table A6.2 Kentucky State Government, USA, requirements pertaining to size of timber props and cross supports when used as the primary means of ground support in underground coal mines Post length (inches) Diameter of round post (inches) Cross-sectional area of split post (square inches) 60 or less 4 13 Over 60–84 5 20 Over 84–108 6 28 Over 108–132 7 39 Over 132–156 8 50 Over 156–180 9 64 Over 180–204 10 79 Over 204–228 11 95 Over 228 12 113 Note: 1 in. ¼ 25.4 mm

Kentucky, USA References Legislation in the USA state of Kentucky Kentucky State Government. (2013). 805 KAR 5:070. (Kentucky State Government 2013) requires Minimum requirements for roof support and the roof that when timber props are used with cross control plan approval process. U.S.: Kentucky supports as the primary means of support, the Administration Regulations. minimum diameter of round props shall be as Menzies, R. A. (c1970). Roof support in coal mines. Sydney: NSW State Government. recorded in Table A6.2. Shepherd, J., & Lewandowski, T. (1994). Improving pillar extraction safety. ACIRL Report OGE 0389/ FINAL. Melbourne: ACARP/AMIRA. Wagner, H. (1994). Coal strata control handbook (Unpublished). Appendix 7: Standard Work Procedure for Setting a Timber Prop

Standard Work Procedure (vi) Wood saw (bushman’s hand saw or air chain saw). (vii) Temporary supports. Note 5. Materials (i) Timber props of adequate length. This example of a Standard Work Proce- (ii) Timber end plates (foot plates/head dure (SWP) for setting a timber prop in an plates/caps/lids). underground coal mine should be risk (iii) Timber wedges. assessed against site specific conditions 6. Inspections and Supervision and modified if required in order to achieve (i) Workplace inspected by a mine official safe and effective outcomes. before persons start work. (ii) Workplace inspected by persons setting Requirements prop before starting work and regularly during work. 1. Personnel (iii) Instructions issued as to where props are (i) Minimum of 2 persons. to be installed. 2. Training (i) Manual handling. Procedure (ii) Use of chain saw. (iii) Testing of roof and ribs. 1. Verify that the work place is safe. 3. Personnel Protective Equipment (i) Check that area has been inspected by a (i) Standard issue. supervisor and declared safe for (ii) Ear protection. persons to enter. (iii) Gloves. (ii) Visually check area from a safe (iv) Safety glasses. distance. 4. Tools (iii) Listen for sounds of movement and (i) Sounding and barring down tool. instability. (ii) Pointed nose shovel. (iv) Sound roof from a safe location. A safe (iii) Measuring stick. distance is based on not being in line- (iv) Chalk (white) or crayon (red). of-fire if the roof falls while being (v) Sledge hammer (6–7kg). sounded.

# Springer International Publishing Switzerland 2016 597 J.M. Galvin, Ground Engineering - Principles and Practices for Underground Coal Mining, DOI 10.1007/978-3-319-25005-2 598 Appendix 7: Standard Work Procedure for Setting a Timber Prop

(v) Use a timber-based tool for sounding (to verify prop can be placed into coal roof and a steel-based tool for niche). sounding stone roof. A dull thud (iv) When setting more than one prop at a indicates that the immediate roof is time, mark the prop number on the stick parting from the rock mass. after each measurement is taken. (vi) If temporary support is required, it must (v) Any prop that has a diameter greater be set without venturing out under than 140 mm should be cut an extra strata that is not secure. 10 mm short to provide the clearance 2. Look for a niche or ridge in the roof at or to expedite its setting and to accommo- close to the target site. date the wedge. (i) The niche has to have an open side so 7. Cut prop to length. that the hammer can hit the wedge clean (i) Cut props from an elevated position. and not bounce off the roof first. Prefer- This may be in a timber pod, over a able roof feature is a small ripple or tripod, or by using one prop as a support ridge. rest for another. (ii) If setting a prop beneath a keystone, (ii) Use a bushman’s saw if not trained in near enough is not good enough. the use of a chain saw. 3. Mark prop location if it is not readily identi- (iii) Prop ends should be cut square. This fiable, especially if other persons are to set may require cutting off both ends. Oth- the prop. erwise cut off the end with the smallest (i) Use a chalk or red crayon cross on the diameter. roof or, preferably, a chalk cross or 8. Subject to prop weight and physical number on a wooden wedge placed on conditions, two or more persons may be the floor where the base of the prop is to required to manually handle the prop. be located. (i) Where more than one person is required (ii) Experienced miners will often mark the they must lift together and both carry measuring stick with a corresponding from the same side. number at the required length of (ii) At the setting location, one person is to the prop. place the larger end of the prop in the 4. Clear down to a solid coal or floor, prefera- correct floor position and then both bly level, beneath niche or ridge. persons are to lift the prop up to its (i) Location can be determined by dropping vertical position. an identifiable piece of stone or coal 9. Manoeuvre top of prop into niche or up from the roof location to the floor. against ridge. (ii) If a foot plate is being used, ensure area 10. Place wedge into position from a direction cleared is large enough to accommodate that results in prop being restrained by niche the foot plate. or ridge as the wedge is being 5. Set foot plate if required. hammered home. 6. Measure floor to roof. 11. Tap wedge with hammer until it starts to bite (i) If using a foot plate, place it before into prop. measuring. 12. Verify that prop is vertical. Eyeball from (ii) Remember to allow for any head plate. front and side. (iii) Use a measuring stick and make sure it 13. Set wedge tight, taking care to continue to has clearance out of any roof niche keep prop vertical. Appendix 7: Standard Work Procedure for Setting a Timber Prop 599

Variations • If a head plate is required in high workings, nail it to the prop prior to lifting the prop into • If roof is uniform or a head plate is being used, position. the prop may need to be periodically tapped back into a vertical position as the wedge is being set. Completion of Work • If a second person is used to steady the prop until the wedge is set, that person must posi- 1. Place all off-cuts in timber pod for removal tion themself out of the line of ﬁre of the from mine or in a place where they do not person setting the wedge. All other persons present a trip hazard. must keep well clear of the hammer swinger. 2. Collect all tools and place with remaining • In high workings, where the top of the prop timber props. cannot be reached or where the wedge cannot 3. Document/report number and location of be set in an ergonomic manner, the wedge props set. may need to be set at the base of the prop. A 4. Document/report any hazards encountered clear access needs to be provided for the ham- during the work. mer to be able to hit the wedge. 5. Pass on documents/reports to supervising mine ofﬁcial. Appendix 8: Derivation of Geometric Relationship for Deflection of a Chord

Mathematical Derivation α3 α5 and Sin ðÞ¼α α À i þ i À ... i i 3! 5! The geometry and trigonometry associated with If αi is small, say less than 0.1 radians, then to the formulation of the concept of mechanical sufficient accuracy for engineering purposes: α2 advantage is shown in Fig. A8.1. The vertical i CosðÞ¼αi 1 À column (beam) A0–C is assumed to be pinned 2! α3 (hinged) at both ends and to deflect in a perfect i Sin ðÞ¼αi αi À arc, with the end points of the line (or roof beam 3hi! α2 abutments) moving inwards with increased À À i U 1 1 2 deflection (or curvature) of the line. Hence, the vi ¼ hi so α3 Uhi α À α À i length of the line, or roof beam, remains constant. 2 i i 6 The amount of inward deflection of the abutments Therefore under the effect of a lateral load, P, is designated α2 ‘Uhi’, with the corresponding mid-point line i Uvi ¼ 2 ¼ 3 ¼ 3 ð : Þ (beam) deflection designated ‘Uvi’. α3 A8 2 Uhi i 2αi θ1 3 Revised derivation of so-called Mechanical Advantage Now, from Fig. A8.1: ÂÃÀÁ Based on Fig. A8.1, the formula for so-called θ U 1 À Cos i ‘mechanical advantage’ at the ith increment of vi ¼ 2 L θi displacement, Uvi=Uhi, is given by Eq. A8.1. ÀÁ θ θ 1 À Cos i To substitute for i in Eq. A8.2 in terms of Uvi, Uvi ¼ ÀÁ2 ð : Þ θ A8 1 rearrange the formula and write it instead in U θ À i hi i 2Sin 2 terms of αi. Therefore θ Letα ¼ i i 2 L L α2 U ¼ ½¼1 À CosðÞα 1 À 1 À i U 1 À CosðÞα vi 2α i 2α 2 Therefore, vi ¼ i i i Uhi 2ðÞαi À 2Sin ðÞαi 2 α2 α4 L α Lαi Lθi i i ¼ : i ¼ ¼ Now, CosðÞ¼αi 1 À þ À ... α 2! 4! 2 i 2 4 8

# Springer International Publishing Switzerland 2016 601 J.M. Galvin, Ground Engineering - Principles and Practices for Underground Coal Mining, DOI 10.1007/978-3-319-25005-2 602 Appendix 8: Derivation of Geometric Relationship for Deflection of a Chord

Fig. A8.1 Geometry and revised trigonometry to more accurately reﬂect the mechanics and mathematics associated with the concept of mechanical advantage presented by Frith (2000) and Colwell (2004, 2012)

Rearranging this result References θ ¼ 8Uvi i 3L Colwell, M. (2004). Analysis and design of rib support (ADRS). A rib support design methodology for Australian Collieries (p. 325). ACARP end of project and substituting this into Eq. A2.2 gives: report C11027. Brisbane: Australian Coal Association Research Program (ACARP). Uvi 3L Colwell, M., & Frith, R. (2012). Analysis and design of ¼ ðA8:3Þ faceroad roof support (ADFRS) (pp. 214). A roof Uhi 8Uvi support design methodology for longwall installation roadways. ACARP end of project report C19008. Therefore Brisbane: Australian Coal Association Research Pro- gram (ACARP). 8ðÞU 2 U ¼ vi ðA8:4Þ Frith, R. (2000). The use of cribless tailgates in longwall hi 3L extraction (pp. 84–92). Paper presented at the 19th international conference in ground control in mining, Morgantown, WV. West Virginia University. Appendix 9: Three Major Incidents in Australia Related to the Design of Pillar Extraction Panels

Some Major Pillar Extraction Incidents method, causing management to modify the in Australia method of extraction. The second plan of extraction called for two Moura No. 4 splits to be driven through the 50 m long by 30 m wide pillars to a height of 2.3 m and then Introduction extracting bottom coal before partially extracting On 16th July 1986, an explosion occurred in a pillar the fenders. This method proved unsuccessful. extraction section at Moura No. 4 Colliery in Irregular sized stooks were left which neither Queensland, Australia, claiming the lives of the fully supported the roof nor permitted the devel- 12 miners in the section. The inquiry found that a opment of full goaf caving. As a result, abutment roof fall had occurred in the goaf and that the pressures increased, as evidenced by rib spall and windblast from the fall blew a mixture of methane, ﬂoor heave. Concern over the method of extrac- air and coal dust into the working area. This was tion was expressed by the District Union Inspec- ignited, with some eight possible sources of igni- tor on 5th June 1986. tion being investigated. The inquiry considered that In the meantime, the company acquired the a ﬂame safety lamp, although properly assembled, surface property over the mining panel. This was the most likely source of ignition. However, removed a major constraint on not causing surface many remain convinced that the source was fric- subsidence. With weighting apparent in the panel, tional ignition due to rock on rock contact during management decided on a system of total extrac- caving of the immediate sandstone roof. tion of the formed pillars. It was decided that:

Overview • extraction would be carried out on a two shift This overview is based on the ﬁndings of the basis; Warden’s Inquiry into the incident (Lynn • three splits would be driven through the pillars et al. 1987). Figure A9.1 shows the mine plan and the fenders so formed totally extracted; associated with the site of the incident. The ﬁrst and plan of extraction called for a single split through • progress would be closely monitored during the formed pillars and extraction of bottom coal the trial period of 2 weeks. to the base of the seam. Thickening of a stone band in the middle of the seam caused a major Total extraction continued without major decrease in the quality of the coal mined by this problems until 16th July, being the date of the

# Springer International Publishing Switzerland 2016 603 J.M. Galvin, Ground Engineering - Principles and Practices for Underground Coal Mining, DOI 10.1007/978-3-319-25005-2 604 Appendix 9: Three Major Incidents in Australia Related to the Design of Pillar Extraction Panels explosion. Observations made by management Colliery in Queensland, Australia, claiming the during an inspection on 15th July confirmed a lives of the 11 miners in various parts of the belief that a goaf fall would shortly occur in the mine. The inquiry found that the explosion was area of total extraction and that this would relieve caused by spontaneous combustion in 512 Panel the abutment loadings being experienced by the igniting a flammable mixture of gas as it was pillars. On the morning of the incident, the passing through the explosive range following Undermanager inspected the goaf edge, observed sealing of the panel a few days earlier. ‘nipping’ of the props and believed a fall was going to occur on that shift. Overview The expected goaf fall occurred soon thereaf- This overview is based on the findings of the ter, with the windblast from the fall blowing a Warden’s Inquiry into the incident (Windridge mixture of methane, air and coal dust from the et al. 1996). A plan of 512 Panel is shown in goaf and inbye working area out to No. 26 - Fig. A9.1. The mine was noted to be gassy and cut-through and perhaps beyond. An explosion prone to spontaneous combustion and 512 Panel occurred which caused extensive damage inbye had been predrained. Prior to about 1986, panels of No. 22 cut-through and the loss of 12 lives. had been designed for the goaf to collapse during The inquiry found that neither of the first two pillar extraction but more recent designs, includ- plans for partial pillar extraction was strictly ing that of 512 Panel, were for the goaf to remain followed and substantially smaller remnant pillars open and be supported by leaving selected pillars were left than planned. It recommended research either totally or partially in place. It was believed and experimentation into the phenomenon of fric- that an open and ventilated goaf would mitigate tional ignition with the purpose of establishing a the risk of spontaneous combustion. standard whereby all strata rock found in Strata control with the need for regional sta- Queensland could be classified according to their bility was a dominant consideration in the design degree of incendivity. Furthermore, it of 512 Panel. The panel was divided into three recommended that pillar extraction be permitted compartments of roughly equal size, separated only with approval of the Mines Department by two rows of large compartment pillars dis- Inspectorate, who should require that: posed across the panel (Fig. A9.2). The headings through these large pillars did not all align with • no departure from the approved method and those through the smaller pillars within each sequence of extraction be undertaken unless compartment. The most inbye cut-through of a minor nature and then only with the (No. 13) and the top return airway were kept specific approval of the Mine Manager; open for ventilation and inspection purposes. • a plan of the method and sequence for The development of 512 Panel commenced in extracting pillars be displayed on notice November 1993 and comprised 7.5 m wide boards on the surface of the mine and in the headings and cross-cuts to form the layout of working panel; and pillars described. The first workings were limited • in the case of a partial extraction method, in height to the top 3 m of the seam with the adequate control to ensure that remnant pillars intention to mine to the full seam height during are not extracted beyond their final design pillar extraction. dimensions. The extraction phase commenced in April 1994 and involved rib-stripping alternative rows of pillars within each compartment so as to leave narrow L-shaped stooks between adjacent rows Moura No. 2 Colliery, Australia of intact pillars. This was, in effect, a ‘take a row, leave a row’ method of pillar extraction. The Introduction extraction phase also involved the systematic On 7th August 1994, an explosion occurred in a mining of approximately 1.5 m of bottom coal partial pillar extraction section at Moura No. 2 by ramping down in the exposed coal floor to the Appendix 9: Three Major Incidents in Australia Related to the Design of Pillar Extraction Panels 605

the panel together with certain beliefs concerning panel life in relation to an assumed spontaneous combustion incubation period. • While no one feature of the design and operation of 512 Panel was identified as directly causing the development of a heating, a number were considered less than desirable in that respect. • The first of these was the amount of loose coal left from the mining process, fracturing of the ribs and stook instability. Both of these were considered undesirable from the point of view of spontaneous combustion management. • While loose coal is inevitably left with any method of extraction, the particular way bottom coal was extracted in 512 Panel by ramping down probably left greater quantities than had been the case with other methods of extraction. • This situation was worsened by limiting the length of ramps since a certain quantity of cut, but unrecovered, coal was left in each ramp. These significant quantities of loose coal in the ramp areas would likely not be effectively ventilated. This may have been exacerbated by local roof falls burying the unrecovered coal. • In addition, high ribs adjacent to the ramp areas were prone to collapse, giving rise to accumulation of loose coal at the sides of stooks and pillars. The stresses induced on remnant pillars would have been sufficient to cause some fracturing of the coal giving rise to the potential for the ingress of air and so the development of a deep seated heating. Fig. A9.1 Plan of Moura No. 4 incident site (after Lynn • While a relatively high ventilation quantity et al. 1987) # State of Queensland. Department of Natural was available in the 512 Panel it is very likely Resources and Mines 2013 that, because of large open areas, ventilation was somewhat sluggish in the goaf. Although sluggish ventilation may well have been ade- base of the seam with the remote controlled con- quate to effectively ventilate the goaf, if the tinuous miner. intent of the panel ventilation design had been The inquiry determined that: adhered to and had other factors not intruded. Those other factors, however, caused undesir- • The failure to prevent the development of a able (from the point of view of the prevention heating in 512 Panel was attributed to a num- of a heating) loss of, or variation in, ventila- ber of aspects of the design and operation of tion to parts of the goaf. 606 Appendix 9: Three Major Incidents in Australia Related to the Design of Pillar Extraction Panels

Fig. A9.2 Plan of Moura No. 2 incident site (After Windridge et al. 1996) # State of Queensland. Department of Natural Resources and Mines 2013 Appendix 9: Three Major Incidents in Australia Related to the Design of Pillar Extraction Panels 607

• The intent of the ventilation design was that Overview holes in the stoppings between the back row This overview is based on the ﬁndings of an of pillars would act, in effect, as regulators to investigation into the incident detailed in Mine balance the ventilation across all parts of the Design Guideline MDG 1007 produced by the goaf. In practice, however, there was evidence NSW Government (MDG-1007 1996). The mine that these were affected by roof falls or local plan associated with the site of the incident is strata instability and that their function was, at shown in Fig. A9.3. The investigation reported times, compromised. that: • There would inevitably be areas in the goaf which were likely to have been less than effec- • Although some extraction panels may have tively ventilated, notably in cross cuts between been ventilated without bleeders, it was the headings and in the corner of the L shaped most common practice at Endeavour Colliery remnant pillars. These would have been fertile to ventilate goaf areas with bleeder returns. areas for the development of a heating. • The pillar extraction area worked prior to 300 Panel was ventilated ‘over and through The inquiry recommended that legislation be the goaf’. amended to make it a requirement that spontane- • When 300 Panel was designed, there was an ous combustion be speciﬁcally included as a intention to form a bleeder return by holing factor to be considered and evaluated when into the Buff Headings. This did not prove applying for approval to conduct secondary possible due to the Buff Headings subse- extraction. quently being used to store water pending the installation and approval of surface pumping outlets. • Poor roof conditions prevented an attempt to Endeavour Colliery, Australia skirt around the water accumulation.

Introduction Conclusions included: On the 28 June 1995, an explosion occurred in 300 pillar extraction Panel at Endeavour Colliery • There was a failure of panel design, develop- in NSW Australia. There were 30 miners under- ment and review processes to recognise and ground at the time, including 8 in the pillar effectively treat the hazard presented by the extraction crew who, despite varying injuries potential for accumulation of gas in the and disorientation arising from lack of visibility, 300 Panel goaf and the possibility of found their way out of the panel. Investigations windblast. into the incident found that a goaf fall had • There was a failure of persons on-shift and, in expelled a ﬂammable mixture of gas into the particular, those in positions of supervision workplace, where it was ignited by a likely but and control, to recognise the potential hazard unconﬁrmed source, being a shuttle car cable represented by occurrences of gas and an back-to-back electrical connector. imminent large fall of roof in the goaf. 608 Appendix 9: Three Major Incidents in Australia Related to the Design of Pillar Extraction Panels

Fig. A9.3 Plan of Endeavour Colliery incident site (from MDG-1007 1996) Appendix 9: Three Major Incidents in Australia Related to the Design of Pillar Extraction Panels 609

References MDG-1007. (1996). Explosion at Endeavour Colliery, 28 June 1995, summary of investigation. Sydney: NSW State Government. Lynn, K. P., Maitland, J., Jones, H., Ross, K., & Kathage, Windridge, F. W., Parkin, R. J., Neilson, P. J., Roxborough, B. A. (1987). Report on an accident at Moura F. F., & Ellicott, C. W. (1996). Report on accident at No. 4 Underground Mine on Wednesday, 16th July, Moura No. 2 Underground Mine on Sunday, 7 August 1986 (pp. 34). Brisbane: Queensland State Government. 1994. Brisbane: Queensland State Government. Appendix 10: Advantages, Disadvantages and Operational Aspects Relating to Mobile Roof Supports

Mobile Roof Supports (MRS) reduced support capacity and density and exposure to risk in setting timber. Advantages and Disadvantages • Increase the rate of pillar extraction and productivity. Advantages of MRS • Reduction in manual handling injuries due to, Disadvantages of MRS typically, a 90 % reduction in timber prop • May require a proven system of extraction to usage. be compromised by changing dimensions or • Remove the need for persons to work at an sequences in order to incorporate MRS. active goaf edge. • Loss of roof monitoring and warning of • Remotely controlled, removing operators back impending goaf fall provided by timber props. from the face line and out of intersections. • Susceptible to damage in massive roof • Provide a higher support density and level of conditions, especially when delayed caving roof coverage than timber props. occurs. • Quicker to set than timber. • Vulnerable to being damaged by the continu- • Can be set under unsupported roof that would ous miner. otherwise be out of bounds when using timber • Introduces additional risks associated with breaker props and rock bolt breaker lines – cable handling and recovery of a MRS particularly applicable when 3 MRS are used immobilised under unsupported roof or to lift left and right. trapped by a fall of ground. • Improved stability. Unlike timber props, can- • May cause operations to stop in the event of a not be displaced by roof or rib falls and capa- breakdown. ble of handling eccentric loads and lateral • Operators can become over-conﬁdent and displacements. complacent, acquiring a false sense of secu- • Positive set load. rity. In three of the ﬁve fatalities in MRS • Capability to yield. sections to 2006 in Kentucky, USA, the • Can be repositioned to suit circumstances. deceased were standing next to the MRS • Accelerate the mining cycle, thus providing units in the active intersection after extracting less time for ground conditions to deteriorate. the last pushout stump, or stook (Marshall • Capacity to extract coal in roof conditions that Miller and Associates 2006). would be abandoned if using timber due to

# Springer International Publishing Switzerland 2016 611 J.M. Galvin, Ground Engineering - Principles and Practices for Underground Coal Mining, DOI 10.1007/978-3-319-25005-2 612 Appendix 10: Advantages, Disadvantages and Operational Aspects Relating to Mobile Roof Supports

Operational Practices depressurised. Operators need to be made aware that the setting of a MRS can cause Operational practices should be detailed in a failure of immediate roof skin or beam. Standard Work Procedure (SWP) that has been • When setting a MRS to the roof, set the front developed with operator input and subjected to legs first to deflect any broken bolt heads risk assessment. Regard may be had to the fol- away from the workplace. lowing guidance material and features of many • When lowering a MRS, lower the rear legs SWPs relating to the use of MRS units in pillar first to allow any debris to fall to the rear of extractions: the machine so it does not impede tramming of the unit. • Guidelines: • Clean up loose material in front of the units – MDG 1005: Manual on Pillar Extraction in using the continuous miner. NSW Underground Coal Mines • MRS units in an active mining area should be (MDG-1005 1992). advanced in a leap frog manner, in intervals – MDG 5002C: Guideline for the Use of not exceeding half a canopy length (and less Remote Controlled Mining Equipment in poor ground conditions). in Underground Coalmines • Procedures should be pre-planned and risk (MDG-5002C 2011). assessed for dealing with situations where units • Manual control should only be used for main- breakdown or become immobilised or buried. tenance purposes. • When recovering a partially or totally buried • During lifting: MRS unit, the canopy should not be lowered – MRS units should be kept as close as prac- until alternative supports have been set to tical to the solid abutment without imped- prevent the goaf flushing in further. ing the operation of the continuous miner. – MRS units should be kept at least 0.3 m apart to avoid becoming interlocked. References – The number of persons working in the vicinity of the continuous miner and the Marshall Miller & Associates. (2006). Retreat mining MRS units should be kept to a minimum practices in Kentucky. Lexington. and their designated standing positions MDG-1005. (1992). MDG 1005: Part 1 and part 2. Man- clearly identified. ual on pillar extraction in NSW underground coal • At all times, it is good practice to stay well mines. Sydney: NSW State Government. MDG-5002C. (2011). Guideline for the use of remote back (preferably, at least 6 m) from a MRS but controlled mining equipment in underground particularly when it is being pressurised or coalmines. Sydney: NSW State Government. Appendix 11: A Selection of Design Requirements and Guidelines Relating to Controlling Surface and Aquifer Water Inflow

Table A11.1 Examples of regulations, guidelines and practices relating to extraction under water bodies and aquifers (extended and modified from Byrnes 1999) Minimum Target carboniferous maximum strata tensile Country Minimum cover thickness strain Design conditions References Australia 40 m – Up to 50 % under the sea Kapp and extraction by bord and Williams pillar. (1972) 65 m – Bord and pillar beneath water storage dams. Bord and Pillar – 46 m – First workings – no caving Wardell of solid rock head Pillar size as prescribed by (1975) legislation for mining under land Panel and Pillar partial – 7.5 mm/m Partial extraction extraction – 46 m of - The maximum width of solid rock head any totally extracted panel shall not exceed 0.3 times the solid rock head cover thickness. - The minimum width of any abutment pillar between extraction panels shall be 8 times its height or 0.12 times the solid rock head cover, whichever is greatest. - No total extraction or pillar extraction permitted within a distance of 46 m of any known fault having a vertical displacement >3 m or dyke having a width >6m Longwall– 46 m of – 7.5 mm/m No total extraction or solid rock head and pillar extraction permitted 60 m of solid rock head within a distance of 46 m cover for each metre of of any known fault having extracted height a vertical displacement >3 m or dyke having a width >6m (continued) # Springer International Publishing Switzerland 2016 613 J.M. Galvin, Ground Engineering - Principles and Practices for Underground Coal Mining, DOI 10.1007/978-3-319-25005-2 614 Appendix 11: A Selection of Design Requirements and Guidelines Relating to Controlling Surface ...

Table A11.1 (continued) Minimum Target carboniferous maximum strata tensile Country Minimum cover thickness strain Design conditions References Austria 290 m – – Total extraction Byrnes (1999) Canada 213 m – 6 mm/m Total extraction Garritty (Nova (1983) Scotia) 213 m and 100 m of 7.7 mm/m Total extraction Kapp and solid rock head cover Williams for each metre of (1972) extracted height Byrnes (1999) Canada 122 m Total extraction Byrnes (Vancouver Extracted (1999) Island) thickness ¼ 1.5 m Chile 150 m 5 mm/m Total extraction Kapp and Williams (1972) Garritty (1983) India – – 3 mm/m Total Extraction Saxena A higher strain limit may and Singh be considered if (1982) superincumbent strata >35 % shale Japan 60 m 8 mm/m Maximum mining height Garritty at minimum rock head (1983) cover ¼ 0.8 m Turkey 160 m – – – Biro¨n, 1964 UK Panel and Pillar – 60 m 45 m 10 mm/m Partial extraction NCB (1968) NCB (1971) Longwall – to seabed – 60 m 10 mm/m Maximum mining height NCB 105 m at minimum rock head (1968) cover ¼ 1.7 m NCB (1971) Longwall – to base of – – – NCB aquifer with inrush (1975) potential – 45 m Look at legislation and guideline USA 60 ft for each foot of – 8.75 mm/ Total extraction Babcock extraction height m and (~60m/m) Hooker (1977) 60 m of solid rock head – 8.75 mm/ Total extraction Byrnes cover for each metre of m (1999) extracted height Yugoslavia 108 m – – Byrnes (1999) Table A11.2 A selection of proposals for the thickness of zones associated with hydrogeological models (extended and modified from Forster 1995) Thickness of deformation Caved Fractured Constrained Surface Author Country zone zone+ zone* zone Remarks Kenny (1969) UK 2–4 t – – – Caving observations Silitsa and USSR – 16 t 4 t – Measured results Vasilenko using dyes (1969) Kapp and Australia – <30 m – 15 m (50 ft Zone thicknesses are Williams (assumed – adopted only estimates (1972) by authors by authors (assumptions) to be from 100 ft) Orchard, 1969) Ropski and Poland 1.5–2 t 3–3.5 t – – Borehole observations Lama (1973) Orchard (1974) UK 6–9 m 18–36 m 30 m <30 m Constrained zone should contain 50 % shale Morton (1975, Australia <30 m 34 t (94 m) – 12 m Based on 1976) (Wongawilli measurements of and Kemira) permeability and piezometric pressure Wardell (1975) Australia <5t <10 t 50 t-S S S ¼ assumed surface (Newcastle) zone thickness NSW Wardell Australia 10 t 60 m 12–15 m Recommendations (1973, 1976) (NSW South based on overseas Coast) experience Singh & UK 3–6 t 30–58 t 9–27 m <15 m Constrained zone Kendorski thickness depend on (1981) lithology Holla and Australia 2 t 10–13 t – – Borehole anchors Armstrong (NSW Hunter (36–45 m) used to determine (1986) Valley) strains Singh (1986) UK 3 t 100t/ 8t <15 m Weak strata (3.1t + 5) 5 t 100t/ 15 t 15 m Strong strata (1.2t + 2) Kesseru (1984) Hungary – 20–40 m 15–25 m – Field experience Kesseru et al. (1987) t seam thickness *includes caved zone thickness + recommended safe distance for subaqueous mining

Table A11.3 Summary of recommendations concerning strata that comprises the constrained zone (after Forster and Enever 1991) Author Remarks Babcock and Hooker (1977) Solid strata with no alluvial or marine sediments Orchard (1974) Should contain 50 % impermeable shale and siltstone Wardell (1975) Should contain beds of naturally low permeability Reynolds (1976) Narrabeen Group rocks (NSW South Coast) Singh and Kendorski (1981) Should contain at least one bed with low permeability Garrity (1983) Cover depth >100 m, at least one third of which should be sandstone (for competence), no faults – based on observations in mines Bhattacharya and Gurtunca Should contain at least one bed with low permeability, no open cracks or ﬁssures, no (1984) faults or other weakness planes

Kesseru et al. (1987) Should contain impermeable beds with σmin > σw (σw ¼ piezometric pressure) Kesseru (1988) 616 Appendix 11: A Selection of Design Requirements and Guidelines Relating to Controlling Surface ...

References Morton, W. H. (1975). Groundwater studies related to mining under surface reservoirs in the Southern Coal- field – Part 1. Report to inquiry into coal mining Babcock, C. O., & Hooker, V. E. (1977). Results of under stored waters for Department of Mines NSW. research to develop guidelines for mining near surface Electricity Commission of NSW. and underground bodies of water. Information circu- Morton, W. H. (1976). Groundwater studies related to lar IC 8741. Denver, CO: U.S. Bureau of Mines. mining under surface reservoirs in the Southern Coal- Bhattacharya, A. K., & Gurtunca, R. G. (1984). Investi- field – Part 2 Final report. Report to inquiry into coal gation of subsurface subsidence. NERDDP end of mining under stored waters for Department of Mines grant report no. 278. NERRDP. NSW. Electricity Commission of NSW. Biro¨n, C. (1964). Denizalti Ko¨mu¨r isletmecilig˘i ve Kozlu NCB. (1968). Working under the sea. Mining Department Bo¨lgesine Tatbikiyeti (Undersea coal mining and its Instruction PI 1968/9. application to Kozlu Coal Mine – in Turkish). E.K.I. NCB. (1971). Working under the sea. Mining Department Insangu¨cuËg˘itm Mu¨du¨rlu¨gu¨ Yayina Instruction PI 1968/8 – Revised 1971. No. 11, Zonguldak (E.K.I Publication of Directorate NCB. (1975). Subsidence engineers handbook (2nd ed.). of Manpower Training, No. 11). Zonguldak: London: National Coal Board. E.K.I. Insangu¨cu¨ Eg˘itm Mu¨du¨rlu¨gu¨ Yayina. Orchard, R. J. (1969). The control of ground movements Byrnes, R. P. (1999). Longwall extraction beneath cata- in undersea mining. The Mining Engineer, 128, ract water reservoir. MEngSc thesis (Geotechnical 259–273. Eng), University of New South Wales, Sydney. Orchard, R. J. (1974). Statement to inquiry into coal Forster, I. R. (1995). Impact of underground mining on the mining under stored waters on behalf of Department hydrogeological regime, Central Coast NSW (pp. of Mines. NSW. Electricity Commission of NSW. 156–168). Paper presented at the conference on engi- Reynolds, R. G. (1976). Coal mining under stored waters neering geology of the Newcastle-Gosford Region. – Report on the inquiry into coal mining under or in Australian Geomechanics Society. the vicinity of stored waters of the Nepean, Avon, Forster, I. R., & Enever, J. (1991). Hydrogeological Cordeaux, Cataract and Woronora reservoirs, New response of overburden to underground mining – Cen- South Wales. Sydney: Department of Mines, NSW tral Coast New South Wales. ISBN 0730569640 (v. 1) State Government. & ISBN 0730569888 (v. 2). Sydney: Office of Energy, Ropski, S., & Lama, R. D. (1973). Subsidence in the near- NSW Government. vicinity of a longwall face. International Journal of Garritty, P. (1983). Water flow into undersea mine Rock Mechanics & Mining Science & Geomechanics workings. International Journal of Mining Engineer- Abstract, 10(2), 105–118. ing, 1(3), 237––251. doi: 10.1007/BF00881614 Saxena, N. C., & Singh, B. (1982). Subsidence behaviour Holla, L., & Armstrong, M. (1986). Measurement of of coal measures above bord and pillar workings. subsurface strata movement by multi-wire borehole Paper presented at the symposium on strata mechan- instrumentation. Bull. Proc. AusIMM, 291(7), 65–72. ics, Newcastle-Upon-Tyne, 283–285. Elsevier. Kapp, W. A., & Williams, R. C. (1972). Extraction of coal Silitsa, I. G., & Vasilenko, G. T. (1969). Determining safe in the Sydney Basin from beneath large bodies of working depth below quicksand in Western Donbass. water (pp. 77–87). Paper presented at the AusIMM Ugol’Ukrainy (In Russian). annual conference, Newcastle. AusIMM. Singh, M. M., & Kendorski, F. S. (1981). Strata distur- Kenny, P. (1969). The caving of waste on longwall faces. bance prediction for mining beneath surface water International Journal of Rock Mechanics & Mining and waste impoundments. Paper presented at the 1st Science & Geomechanics Abstracts, 6, 541–555. conference ground control in mining, Morgantown, Kesseru, Z. (1984). Empirical and theoretical methods WV, 77–91. West Virginia University. for designing soft semi-permeable protective Singh, R. N. (1986). Mine inundations. International barriers. International Journal of Mine Water, 3(2), Journal of Mine Water, 5(2), 1–28. 1–13. Wardell, K. (1973). Statement to inquiry into coal mining Kesseru, Z. (1988). Remarks, proposals on undermining under stored waters on behalf of the mining water storages/dams relating to the question of Dams companies. NSW: Electricity Commission of NSW. Safety Committee of N.S.W. Australia. Sydney: NSW Wardell, K. (1975). Mining under tidal waters. Sydney: Department of Mines Ministry for Mines and Power, NSW State Kesseru, Z., Szilagyi, G., Szentai, G., Havasy, I., & Toth, Government. I. (1987). Exploration and evaluation of the Wardell, K. (1976). Further statement to inquiry into coal hydrogeological conditions of coal deposits where mining under stored waters on behalf of mining the water danger strongly depends on mining method. companies. NSW: Electricity Commission of NSW. Unpublished. Appendix 12: A Selection of Classification Schemes Relating to Subsidence Impacts on Structures

Table A12.1 National Coal Board system for classifying subsidence damage

Adapted from NCB (1975)

# Springer International Publishing Switzerland 2016 617 J.M. Galvin, Ground Engineering - Principles and Practices for Underground Coal Mining, DOI 10.1007/978-3-319-25005-2 618 Appendix 12: A Selection of Classification Schemes Relating to Subsidence Impacts on Structures

Fig. A12.1 National Coal Extension metres Board system for classifying subsidence 0.03 0.06 0.12 0.18 impact based on 5 relationship between the length of a structure and horizontal ground strain (Adapted from NCB 4 Category 5 (1975)) Very Severe

3 Category 4 Severe

Category 3 Appreciable

Strain mm/m 2 Category 2

Very Slight or NegligbleSlight Category 1 1

0 0255075100 125 150 Length of structure in metres Appendix 12: A Selection of Classification Schemes Relating to Subsidence Impacts on Structures 619

Table A12.2 Graduated design guidelines of NSW Mine Subsidence Board as at 2001

(continued) 620 Appendix 12: A Selection of Classification Schemes Relating to Subsidence Impacts on Structures

Table A12.2 (continued)

(continued) Appendix 12: A Selection of Classification Schemes Relating to Subsidence Impacts on Structures 621

Table A12.2 (continued) 622 Appendix 12: A Selection of Classification Schemes Relating to Subsidence Impacts on Structures

Table A12.3 Revised classification of subsidence impacts to houses based on extent of repairs (Waddington 2009) Repair category Extent of repairs Nil No repairs required R0 adjustment One or more of the following, where the damage does not require the removal or replacement of any external or internal claddings or linings: Door or window jams or swings, or Movement of cornices, or Movement at external or internal expansion joints R1 very minor One or more of the following, where the damage can be repaired by filling, patching or painting repair without the removal or replacement of any external or internal brickwork, claddings or linings:- Cracks in brick mortar only, or isolated cracked, broken, or loose bricks in the external façade, or Cracks or movement < 5 mm in width in any external or internal wall claddings, linings, or finish, or Isolated cracked, loose, or drummy floor or wall tiles, or Minor repairs to any services or gutters R2 minor repair One or more of the following, where the damage affects a small proportion of external or internal claddings or linings, but does not affect the integrity of external brickwork or structural elements:- Continuous cracking in bricks <5 mm in width in one or more locations in the total external façade, or Slippage along the damp proof course of 2–5 mm anywhere in the total external façade, or Cracks or movement 5 mm in width in any external or internal wall claddings, linings, finish, or Several cracked, loose or drummy floor or wall tiles, or Replacement of any services R3 substantial One or more of the following, where the damage requires the removal or replacement of a large repair proportion of external brickwork, or affects the stability of isolated structural elements:- Continuous cracking in bricks of 5–15 mm in width in one or more locations in the total external façade, or Slippage along the damp proof course of 5–15 mm anywhere in the total external façade, or Loss of bearing to isolated walls, piers, columns, or other load-bearing elements, or Loss of stability of isolated structural elements R4 extensive One or more of the following, where the damage requires the removal or replacement of a large repair proportion of external brickwork, or the replacement or repair of several structural elements:- Continuous cracking in bricks > 15 mm in width in one or more locations in the total external façade, or Slippage along the damp proof course of 15 mm or greater anywhere in the total external façade, or Relevelling of building, or Loss of stability of several structural elements R5 Re-build Extensive damage to house where the MSB and the owner have agreed to rebuild as the cost of repair is greater than the cost of replacement Appendix 12: A Selection of Classification Schemes Relating to Subsidence Impacts on Structures 623

Table A12.4 Probabilities of subsidence impacts based on curvature and type of construction (Waddington 2009) Repair category Radius of curvature (km) No repair or R0 R1 or R2 R3 or R4 R5 Brick or brick-veneer houses with Slab on Ground >50 90 ~ 95 % 3 ~ 10 % 1 % <0.1 % 15–50 80 ~ 85 % 12 ~ 17 % 2 ~ 5 % <0.5 % 5–15 70 ~ 75 % 17 ~ 22 % 5 ~ 8 % <0.5 % Brick or brick-veneer houses with Strip Footing >50 90 ~ 95 % 3 ~ 10 % 1 % <0.1 % 15–50 80 ~ 85 % 7 ~ 12 % 2 ~ 7 % <0.5 % 5–15 70 ~ 75 % 15 ~ 20 % 7 ~ 12 % <0.5 % Timber-framed houses with ﬂexible external linings of any foundation type >50 90 ~ 95 % 3 ~ 10 % 1 % <0.1 % 15–50 85 ~ 90 % 7 ~ 13 % 1 ~ 3 % <0.5 % 5–15 80 ~ 85 % 10 ~ 15 % 3 ~ 5 % <0.5 %

development of improved methods of subsidence References impact assessment. ACARP end of project report no. C12015. Brisbane: Australian Coal Association NCB. (1975). Subsidence engineers handbook (2nd ed.). Research Program (ACARP). London: National Coal Board. Waddington, A. A. (2009). The prediction of mining induced movements in building structures and the Appendix 13: Examples of Risk Management Based Statutory Requirements Relevant to Developing Ground Control Management Plans

NSW Coal Mine Health and Safety (ii) the dimensions of the support, Regulation, 2006 (iii) the locations where there are varying types of supports in use, 32 Contents of Major Hazard (iv) the distance between supports, Management Plan: Strata Failure (v) the maximum distance roadways can Management Plan be advanced before support is installed, For the purposes of section 36 of the Act, a major (vi) the means of roadway support hazard management plan in relation to a major required to be installed in a manner hazard comprising hazards arising from strata such that they may be readily under- failure must make provision for the following stood by those required to install the matters: roadway support, (g) other information necessary to enable an (a) the estimation of the geological conditions employee to install support according likely to be encountered in roadway to the requirements of the management development, plan, (b) the assessment of the stability of roadways (h) safe, effective and systematic work to be developed in those geological methods for the installation, and conditions, subsequent removal when required, of (c) the recording of geological conditions that the roadway support (including support may affect roadway stability, in connection with the carrying out of (d) the development of support measures that roof brushing operations or the recovery will provide roadway stability in those of plant), geological conditions, (i) the availability of adequate plant and (e) calculations (including maximum road- resources to effectively install or remove way width and the minimum dimensions the roadway support, of coal pillars) to determine the probabil- (j) the monitoring of the stability of roadways ity of instability to be assigned to any coal after development and support pillar, consistent with the pillar’s role or installation, roles over its life, (k) the training of employees in support (f) the preparation and distribution of support design principles, support plan interpreta- plans that clearly describe the following: tion, placement and removal of support, (i) the type of support, understanding the need for and the

# Springer International Publishing Switzerland 2016 625 J.M. Galvin, Ground Engineering - Principles and Practices for Underground Coal Mining, DOI 10.1007/978-3-319-25005-2 626 Appendix 13: Examples of Risk Management Based Statutory Requirements ...

importance of the various support systems 2. The risk assessment must have regard to at and recognition of indicators of change least the following matters— that may affect roadway stability, (a) any surface features, artificial structures (l) the recording of strata failures that have and water reserves that may create a haz- the potential to cause serious injury (such ard if disturbed by the workings; as a notifiable incident under clause 55) to (b) any other workings located in close prox- people, imity above, below or adjacent to the (m) a description of the following features and proposed second workings, whether in any special provision made for them: the same or an adjacent mine; (i) any multi-seam workings, (c) the known geology affecting the (ii) any mining that has the potential to intended workings; cause windblast or rapid stress (d) the anticipated gas make; change, (e) the pillar stability; (iii) any mining at depths of less than (f) the proposed method and sequence of 50 m, coal extraction; (iv) any coal pillars with a pillar width to (g) the proposed methods for the pillar height ratio of 4:1 or less, following— (n) a prohibition on people entering an under- (i) strata control and support; ground place at the coal operation that is (ii) ventilation; not supported in accordance with the man- (iii) controlling spontaneous combus- agement plan, unless the person does so tion; for the purpose of erecting support, in (h) support methods necessary to control the which case temporary support must be edges of each goaf area in active used, workings; (o) a prohibition on mining in any place (i) the suitability of the plant, and its at the coal operation unless there is suffi- controls, used for the workings. cient support for the place in accordance with the requirements of the management 318 Standard Operating Procedure plan, (p) a statement that nothing in the manage- 1. An underground mine must have a standard ment plan is to be read as preventing operating procedure for carrying out second the installation of more strata support workings. or support installation at more frequent 2. The procedure must be based on the results of intervals than is required by the the risk assessment mentioned in section 317. management plan. 3. The mine must have a separate procedure for each panel in the mine. QLD Coal Mine Safety and Health 4. However, if the hazards in each panel in a Regulation, 2001 group of panels are the same, the mine may have a standard operating procedure for the 317 Risk Assessment group. 5. The procedure must include provision for 1. The underground mine manager must ensure a establishing— risk assessment is carried out under this sec- (a) methods for the following— tion to decide a safe method of extraction for (i) coal extraction; second workings at the mine before the sec- (ii) strata control and support; ond workings start. (iii) ventilation; Appendix 13: Examples of Risk Management Based Statutory Requirements ... 627

(iv) controlling spontaneous combus- 2. If subsection (1)(a) applies— tion; (a) the underground mine manager must (v) monitoring and recording extrac- ensure a risk assessment for the workings tion progress; and is carried out as soon as practicable after (b) the coal extraction sequence. the change happens; and (b) the standard operating procedure for carrying out the workings in the panel, or 319 Changing Standard Operating group of panels, must be reviewed and, Procedure based on the risk assessment, amended, if necessary. 1. This section applies to an underground 3. If subsection (1)(b) applies, before the change mine if - is implemented— (a) the conditions or hazards in a panel, or (a) the underground mine manager must group of panels, in the mine changes ensure a risk assessment is carried out signiﬁcantly while coal is being for the proposed change; and extracted in the panel or group in second (b) the standard operating procedure for car- workings; or rying out the workings must be amended, (b) it is proposed to signiﬁcantly change a if necessary, based on the risk method for the workings established assessment. under section 318(5)(a). Appendix 14: Sources of Information Relevant to Managing Risk in Ground Engineering

ORGANISATIONS

International Labour Organisation www.ilo.org

Safe Work Australia www.safeworkaustralia.gov.au

Minerals Council of Australia www.minerals.org.au

NSW Minerals Council www.nswmc.com.au

Queensland Mining Council www.qmc.com.au

Tasmanian Minerals Council www.tasminerals.com.au

W.A. Chamber of Mines and Energy www.mineralswa.asn.au Mine Managers Association of www.minemanagers.com.au Australia Minerals Industry Safety and Health www.mishc.uq.edu.au Centre (MISHC) Minerals Industry Risk Management www.mirmgate.com Gateway Australian Coal Association Research www.acarp.com.au Program Cooperative Research Centre Mining http://www.crcmining.com.au/ Ministry of Labour Occupational www.gov.on.ca/lab/ohs Health and Safety - Canada Mine Safety and Health Administration of the US Department www.msha.gov of Labour National Institute for Occupational www.cdc.gov/niosh/ Safety and Health (NIOSH) - USA Health and Safety Executive - UK www.hse.gov.uk/ Mine Health and Safety Council, http://www.mhsc.org.za/ South Africa Safety in Mining Research http://www.dst.gov.za/s-t-landscape/S- Dept. Science and Technology – Sth T%20Funding%20Agencies/SIMRAC Africa

# Springer International Publishing Switzerland 2016 629 J.M. Galvin, Ground Engineering - Principles and Practices for Underground Coal Mining, DOI 10.1007/978-3-319-25005-2 630 Appendix 14: Sources of Information Relevant to Managing Risk in Ground Engineering

STANDARDS International Labour www.ilo.org Organisation Safety and Health in Mines Convention, 1995 ILO C176 (No. 176). US Standards Standard Specification for Roof and Rock Bolts and ASTM F432-10 Accessories Australian/NZ/International www.standards.com.au Standards AS/NZS/ISO 9001: 2008 Quality Management Systems - Requirements AS/NZS/ISO 31000: 2009 Risk Management - Principles and Guidelines Australian Standards www.standards.com.au AS 1470-1986 Health and Safety at Work – Principles and Practices The Design and Use of Reflectorized Safety Signs for AS 1614-1985 Mines and Tunnels Quality System Guidelines. Part 12: Guide to AS/NZS 3905.12: 1999 AS/NZS 9001:1994 for Architectural and Engineering Design Practice Risk Analysis of Technological Systems – Application AS/NZS 3931-1998 Guide. AS 4024-1996 Safeguarding of Machinery AS 4368-1996 Mine Plans – Preparation and Symbols AS/NZS 4801:2001 Occupational Health and Safety Management Systems Occupational Health and Safety Management Systems AS/NZS 4804:2001 – General Guidelines on Principles, Systems and Supporting Techniques Appendix 14: Sources of Information Relevant to Managing Risk in Ground Engineering 631

GUIDELINES

Australian Government http://www.safeworkaustralia.gov.au/sites/SWA Code of Practice for Strata Control in Underground Coal Mines Code of Practice for Inundation and Inrush Hazard Management NSW Government http://www.resources.nsw.gov.au/ Code for Portable Pneumatically Powered Rotary Roof MDG 5 Bolters for Use in Coal Mines MDG 6 Code for Breaker Line Supports for Use in Coal Mines Design Guidelines for the Use of Aluminium in MDG 11 Underground Coal Mines MDG 1003 Wind Blast Code of Practice MDG 1004 Outburst Mining Guideline MDG 1005 Manual on Pillar Extraction MDG 1006 Spontaneous Combustion Management Code MDG 1007 Explosion at Endeavour Colliery MDG 1010 Risk Management Handbook for the Mining Industry MDG 1013 Systems Safety Technique Guide to Reviewing a Risk Assessment of Mine MDG 1014 Equipment and Operations Roof Support Guidelines for Massive Strata MDG 1017 Conditions Guidelines for Determining Withdrawal Conditions MDG 1022 from Underground Coal Mines MDG 1030 Guideline for Raise Boring Operations MDG 3001 Applicant’s Guide to Obtaining an Approval from the Chief Inspector of Coal Mines MDG 3002 Systems Safety Accident Investigation Series Summaries of Reportable Accidents and Dangerous MDG 3003 Occurrences: 1991 onwards. MDG 3004 Review of Reportable Frictional Ignitions of Methane in New South Wales Underground Coal Mines MDG 3012 Safety Alerts and Significant Incident Reports to 1996 - Safety Alerts – Post 1996 MDG 5002 Mine Safety Review Guidelines for the Use of Remote Controlled Mining Equipment MDG 5003 Guidelines for Contractor Occupational Health and Safety Management for New South Wales Coal Mines EDG 1 Guidelines for Borehole Sealing Requirements on Land – Coal Exploration EDG 2 Guidelines for Borehole Sealing Requirements on the Beds of Waterbodies – Coal Exploration - Minerals Industry Safety Handbook Western Australian www.doir.wa.gov.au Government ZMT723RK Underground Barring Down and Scaling Guideline

South African www.dmr.gov.za Government DME 16/3/2/1-A3 Guideline for the Compilation of a Mandatory Code of Practice to Combat Rock Falls and Rockburst Accidents in Tabular Metalliferous Mines 632 Appendix 14: Sources of Information Relevant to Managing Risk in Ground Engineering

LEGISLATION AND REGULATION

NORTH AMERICA Mine Safety and Health Administration www.msha.gov of the US Department of Labour Ministry of Labour Occupational www.gov.on.ca/lab/ohs Health and Safety - Canada UK

Health and Safety Executive - UK www.hse.gov.uk/

AUSTRALIA

Australian Legal Information Institute www.austlii.edu.au

Queensland Legislation www.legislation.qld.gov.au/Legislation.htm

NSW Legislation www.legislation.nsw.gov.au/ Qld Department of Natural Resources www.nrm.qld.gov.au/mines and Mines Mining Warden’s Court of Queensland www.warden.qld.gov.au

WorkCover - Queensland www.workcover.qld.gov.au

NSW Minerals and Petroleum http://www.resources.nsw.gov.au/

WorkCover - NSW www.workcover.nsw.gov.au

Conference of Chief Inspectors of Mines www.agso.gov.au/ccim Appendix 15: Guidelines for Developing a Mine Safety Management System and a Principal Hazard Management Plan

Guidance Material 7. Detail the system for achieving safety objectives. The following summary is based on guidelines 8. Provide for detecting changes in conditions. for preparing a Mine Safety Management System 9. Detail procedures for the conduct of regular (MSMS) and a Hazard Management Plan (HMP) reviews of the operation and adequacy of the produced by the Queensland Department of system. Mines & Energy (Qld Dept. Mines & Energy 1996). A MSMS is not intended to be an additional layer of regulation. Nor does such a system remove any obligation to fulfil statutory Health and Safety Management requirements. Rather, its purpose is to provide System the framework within which a mine site can manage risk, consistent with its statutory Purpose of a MSMS obligations, but with the actual system content and ownership residing with the mine site. As A Mine Safety Management System (MSMS) is such, it is intended to be proactive and broader intended to formalize the process by which a ranging approach than that required by prescrip- mine addresses its principal hazards and other tive legislation. related matters in order to provide a safe work place. A MSMS is expected to: Structure of a MSMS 1. Set out the means by which hazards are identified and risks are assessed. A MSMS should: 2. Identify effective risk control measures which are independent of changes in site personnel. 1. Provide a systematic definition of all the 3. Ensure consistency in the way hazards are actions necessary to allow mining operations controlled. to be carried out safely; 4. Set performance standards. 2. Include, but not be limited to, organizational 5. Provide for the monitoring of performance structures, planning, activities, responsi- standards. bilities, practices, risk identification, audits 6. Set safety objectives for the mine. and reviews;

# Springer International Publishing Switzerland 2016 633 J.M. Galvin, Ground Engineering - Principles and Practices for Underground Coal Mining, DOI 10.1007/978-3-319-25005-2 634 Appendix 15: Guidelines for Developing a Mine Safety Management ...

3. Be based on appropriate codes, standards, design. The types of matters which should be rules, regulations and guidelines. brieﬂy described include:

Therefore, a MSMS could be expected to • Access to the mine include, but not be limited to, the following • Seams mined elements: • Depth of mining • Seam characteristics • Mining methods Introduction • Ventilation • Shift working systems The Introduction should state the overall objec- • Employment tive of the MSMS, establish the framework and ownership of the document and provide guidance as to its use. It may include corporate safety targets and objectives and details of the structure Identification of Principal Hazards of the organisation, including roles and responsibilities of members of the organisation. The methods by which the principal hazards were identified, who was involved in the process, positions title and qualifications of these persons, Scope the scope of the hazard analysis and risk assessment, and the identified principal hazards should The Scope should list all the Hazard Manage- be documented in this section of the MSMS. The ment Plans (HMPs) which apply at the mine. In intent is to establish that the personnel involved general, the hazards should all be identified in the hazard identification were appropriately though a process of risk assessment. In practice, qualified, experienced and competent and that however, some hazards are mandated by legisla- the process was adequately resourced and tion because they present core risks to mining undertaken in accordance with an established operations. Examples of mandated hazards for risk assessment standard. which underground coal mines must prepare a HMP include: Organisational Responsibilities • Mine Atmosphere, incorporating: and Resources – Ventilation Management – Gas Management The purpose of this section is to demonstrate that • Strata Management the organization has allocated sufficient • Spontaneous Combustion Management resources and assigned appropriate responsi- • Fire Control bilities to fulfill the requirements of the MSMS. • Emergency Response Each HMP should have a document owner who is responsible for administration and co-ordination of the HMP.

Mine Characteristics Management Review This section should outline the characteristics of the mine which are relevant to the various HMPs, This section should detail Senior Management’s taking into account both current and future mine responsibility and commitment to review the Appendix 15: Guidelines for Developing a Mine Safety Management ... 635

MSMS at regular intervals in order to ensure its internal personnel and external providers. The continuing suitability and effectiveness, to iden- assignment of responsibilities to a person should tify new hazards where appropriate, and to take into account any statutory obligations of this implement improvements and corrective actions. person.

Developing a Hazard Management Resources Required Plan Identiﬁes the resources that the organisation has A Hazard Management Plan should be developed to put in place in order to meet the requirements in support of the Mine Safety Management Sys- of the HMP. tem to address each principal hazard encountered or likely to be encountered at a mine. It could be expected to include, but not be limited to, the Trigger Action Response Plans (TARPs) following elements: These plans outline trigger points, the actions to be taken for each trigger point and the persons Introduction responsible for implementing these actions. Trigger points can include observations, States the objective and scope of the HMP with measurements or events. respect to the speciﬁc hazard being addressed. Objectives usually encompass the formalization of the systems, standards, procedures and Communications methods in use or to be introduced to ensure effective management and control of the hazard. Details the establishment and maintenance of procedures for:

Identified Hazard (a) Internal communication between the various levels and functions of the mine. Outlines the method by which the hazard was (b) Receiving, documenting and responding to identiﬁed and assessed. relevant communications to the hazard being addressed.

Control Procedures

Identifies the control procedures to be followed Training and the persons responsible for implementing each control. The details which comprise each Identifies the training required to address a spe- control procedure may be contained in separate cific hazard, the persons who are to receive this supporting documents. A control procedure may training, and the establishment and maintenance find application to more than one hazard. of procedures to make employees at each relevant function and level aware of:

Roles and Responsibilities (a) The importance of conformance with procedures and with the requirements of This section should outline the roles, responsi- the HMP; bilities and competencies of all persons having (b) The signiﬁcance safety impacts, actual or accountability under the HMP. This includes potential, of their work activities and the 636 Appendix 15: Guidelines for Developing a Mine Safety Management ...

safety beneﬁts of improved personal (b) Has been properly implemented and performance; maintained. (c) The roles and responsibilities in achieving conformance with procedures and with the This element should include details on how requirements of the HMP, including emer- management is to be informed of the results of gency preparedness and response audits and reviews. requirements; (d) The potential consequences of departure from the HMP. Document Control

Details the establishment and maintenance of Corrective Action procedures which: Details the establishment and maintenance of (a) Assign responsibilities and define processes procedures for: for the creation and modification of documents relevant to the HMP; (a) defining responsibility and authority for (b) Ensure that all documents relevant to the handling and investigating non-conformance; HMP are: (b) taking action to mitigate any impacts (i) Legible; caused; (ii) Dated, including dates of revision; (c) for initiating and completing corrective and (iii) Readily identifiable; preventative actions; (iv) Maintained in an orderly manner; (d) implementing any changes in documented (v) Maintained for any specified period; procedures as a result of corrective and pre- (vi) Readily locatable and accessible; ventative actions; (vii) Periodically reviewed, revised as (e) recording any changes in documented necessary and approved for adequacy procedures. by authorised personnel; (viii) Available, as a current version, at all Review locations where operations essential to the effective functioning of the Details: plan are performed; (c) Ensure that obsolete documents related to (a) The intervals at which the HMP is to be the HMP are: reviewed to ensure its continuing suitabil- (i) All promptly removed from all points ity, adequacy and effectiveness. of issue and points of use or otherwise (b) Procedures for reviewing significant issues assured against unintended use; which arise and their response status. (ii) Suitably identified as being obsolete if they are retained for purposes such as legal proceedings or knowledge Audit preservation.

Details the establishment and maintenance of programmes and procedures for periodically Records auditing and reviewing the HMP in order to determine whether or not the HMP: Details the establishment and maintenance of procedures for the identiﬁcation, maintenance (a) Conforms to planned arrangements for and deposition of health and safety related safety management; records, including training records and the results Appendix 15: Guidelines for Developing a Mine Safety Management ... 637 of audits and reviews. Reference should be made References to provisions for ensuring that safety records: Qld Department of Mines & Energy. (1996). Approved (a) Are legible, identiﬁable and traceable to the standard for mine safety management plan. QMD activity involved; 967386/A. Brisbane: Department of Mines and Energy, Qld State Government. (b) Stored and maintained in such a way that they are readily retrievable and protected against damage, deterioration or loss; (c) Have an established retention time which is recorded. Appendix 16: An Example of a Trigger Action Response Plan (Ground Management on a Longwall Face)

TRIGGER ACTION RESPONSE PLAN – LONGWALL FACE

Level 1 – Condition Green Level 2 – Condition Yellow Level 3 – Condition Orange Level 4 – Condition Red Geology Geology Geology 1. Minor geological structure to 0.5 m 1. Faults converging within 5 to 10 chocks 1. Faults converging within 5 chocks of of each other each other -- 2. Faults within 5 chocks of gateroads 2. Major sandstone unit within 5m of coal 3. Major sandstone lens within 10m of seam coal seam Roof Coal Thickness Roof Coal Thickness Roof Coal Thickness Roof Coal Thickness 1. Greater than 1.0m 1. Less than 1.0m 1. None. Stone visible over up to 10 1. None. Stone visible over more than consecutive chocks but stable 10 consecutive chocks and continues to dribble Visual Visual Visual Visual 1. Normal conditions. Pick marks visible and 1. Roof deteriorating. Fretting, loss of 1. Roof guttering or roof falling to stone 1. Roof fall greater than 1m above cut remain in cut roof or visible parting at visible pick marks. Loss of natural parting bands <1m above cut roof horizon and hading at least 1 web ahead Roof desired horizon above desired cut horizon 2. Break line between canopy tips and face of face. Large quantities of material Conditions 2. Break line at rear edge of chocks 2. Break line over canopy, forward of legs continue to rill in 2. Break line ahead of face. Face being scoured out by falling material Tip-to-Face Tip-to-Face Tip-to-Face Tip-to-Face

TRIGGER 1. Less than 0.75m after chocks advanced 1. Between 0.75 and 1.2m after chocks 1. Between 1.2m and 1.5m after chocks 1. Greater than 1.5m after chocks advanced advanced advanced Chock Set Pressure Chock Set Pressure Chock Set Pressure Chock Set Pressure 1. 350 – 400 Bar 1. Less than 350 Bar 1. Less than 200 Bar over 5 or more consecutive chocks Chock Convergence Chock Convergence Chock Convergence Chock Convergence 1. <50mm/hour 1. Greater than 50mm/hour but less than 1. Greater than 100mm/hour but less than 1. Greater than 200mm/hour 2. No flow or only a few drips from yield 100mm/hour 200mm/hour 2. Shearer barely passes through under valves 2. Some minor fluid flow from yield 2. Continuous fluid flow from yield valves canopies (nearly iron bound) valves over a length of 15 chocks over a length of 15 chocks 3. Continuous fluid flow from yield valves over a length of >15 chocks Visual Visual Visual Visual 1. Some face slabbing ahead of leading drum 1. Minimal cutting required with spall 1. Face slabbing heavily with heavy spall 1. Face slabbing heavily with heavy Face 2. Face spall less than 0.5m occurring greater than 10 chocks ahead of well in advance of leading drum spall well in advance of leading drum Conditions leading drum 2. Face spall 1.1 to 1.5m and behind trailing drum 2. Spall 0.5 to 1.0m 2. Face spall greater than 1.5m Mode of 1. Uni-Di with shearer initiation 1. Uni-Di with auto adjacent controls 1. Uni-Di manual control 1. Keep shearer on tailgate side of affected Operation 2. Cancel shearer initiated chock advance 2. Bi-Di sequence optional in localised area during chocking and push primes in affected area areas 2. Employ Uni-Di manual control if 3. Restrict shearer speed to match chock 3. Cancel shearer initiated chock advance sufficient clearance operators through affected area and push primes in affected area 3. Cancel shearer initiated chock advance 4. Monitor AFC flow to BSL to prevent and push primes throughout affected area blockages 4. Monitor AFC flow to BSL to prevent 5. Restrict shearer speed to match chock blockages operations through affected areas 5. Restrict shearer speed to 50% max through affected area Support 1. Supports advanced 2 chocks behind 1. Single support advance immediately 1. Single support advance immediately 1 Keep shearer on tailgate side of affected Operation leading drum. behind the leading drum behind leading drum area during chocking 2. Positive set in use 2. Double chock where practical 2. Double chock 2. Use manual overrides through affected 3. Sprags set behind trailing drum 3. Set sprags ASAP area 4. Positive set in use except where it 4. Use positive set except where it affects 3. Double chock ASAP affects canopy attitude. Guaranteed set canopy attitude. Chocks should otherwise 4. Set sprags ASAP used in these softer zones – attempt to be set with maximum pressure to maintain 5. Use positive set except where it affects maintain canopy attitude and maximise tip canopy attitude and to maximise tip canopy attitude. Chocks should otherwise pressure. Ensure positive set is turned on pressure. Ensure positive set is turned on be set with maximum pressure to maintain to supports adjacent to yellow zone. to supports outside of orange zone canopy attitude and to maximise tip Positive set to be turned on ASAP when 6. Positive set to be turned on ASAP when pressure. Ensure positive set is turned on

RESPONSE conditions permit. conditions permit. to supports outside of orange and red zones 6. Positive set to be turned on ASAP when conditions permit. 1. Check face alignment each shift and 1. Check face alignment each shift and 1. Check face alignment each shift and 1. Check face alignment each shift and Face correct as required correct as required correct as required under direction of Face correct as required under direction of Face Alignment Supervisor Supervisor after consultation with Longwall Superintendant 1. Roof height and cutting horizon as per 1. Roof height and cutting horizon as per 1. Roof height and cutting horizon as per 1. Roof height and cutting horizon as per Horizon longwall hazard management plans longwall hazard management plans Longwall Superintendant’s instructions. Longwall Superintendant’s instructions. Control

1. Continually check creep 1. Continually check creep 1. Continually check creep 1. Continually check creep Creep Control 2. Creep is <200mm offline subject to MG 2. Fly cut if creep is 200mm to 500mm 2. Correct if creep is over 500mm from 2. Contact Longwall Superintendant roadway alignment from normal but only under Face normal and getting worse but only under before correcting creep in red affected Supervisor’s instructions Longwall Superintendant instructions areas

1. The Face Supervisor has the authority to 1. The Face Supervisor has the authority to 1. The Face Supervisor has the authority to Change move to a higher trigger level move to a higher trigger level move to a red trigger level Condition Up --

1. The Face Supervisor has the authority to 1. The Longwall Superintendant and 1. The Longwall Superintendant in Change revert back to lower trigger level Longwall Coordinator in consultation with consultation with the Geotechnical Condition -- the Geotechnical Engineer have the Engineer has the authority to revert back AUTHORITY Down authority to revert back to a lower trigger to a lower trigger level level

# Springer International Publishing Switzerland 2016 639 J.M. Galvin, Ground Engineering - Principles and Practices for Underground Coal Mining, DOI 10.1007/978-3-319-25005-2 640 Appendix 16: An Example of a Trigger Action Response Plan (Ground Management on a Longwall Face)

TRIGGER ACTION RESPONSE PLAN – LONGWALL FACE

Level 1 – Condition Green Level 2 – Condition Yellow Level 3 – Condition Orange Level 4 – Condition Red

Accountability When a person under a TARP is unavailable, that person’s immediate supervisor is to fulfil the role

1. Operate to set standards and Face 1. Cancel shearer initiated chock advance 1. Cancel shearer initiated chock advance 1. Keep shearer on tailgate side of affected Shearer Supervisor’s Instructions and push primes in affected area and push primes in affected area area during chocking Operator 2. Observe for deteriorating conditions and 2. Reduce shearer speed to match chock 2. Reduce shearer speed to match chock 2. Cancel shearer initiated chock advance report to Face Supervisor, chock operators operators in affected area operators in affected area and push primes in affected area and maingate operator 3. Reduce shearer speed to match chock 3. Maintain set shearer speed operators in affected area 4. Report chock defects to trades 5. Ensure positive set is on 1. Monitor chock automation 1. Operate chocks in auto adjacent control 1. Operate chocks in manual control with 1. Operate chocks in manual control with Chock with positive set isolated when it affects positive set isolated when it affects canopy positive set isolated when it affects canopy Operators canopy attitude (maintain level canopy attitude attitude attitude) 2. Advance chocks immediately behind 2. Advance chocks immediately behind 2. Advance chocks two behind leading leading drum and set sprags ASAP leading drum and set sprags ASAP drum 3. Double chock in affected area ASAP 3. Double chock in affected area ASAP 3. Set sprags ASAP 3. Return to positive set ASAP 3. Return to positive set ASAP 3. Return to positive set ASAP 1. Monitor creep 1. Monitor AFC flow to BSL to prevent Maingate 2. Check system pump pressure, chock set blockages -- -- Operator pressures, positive set pressures, emulsion tank levels 1. Monitor chock conditions and repair or 1. Apply manual applications to overcome 1. Increase AFC tension when stone is report as required maintenance problems causing downtime present on conveyor 2. Check pump pressure in adverse conditions (i.e. bypass cooling Trades -- 3. Identify and report defective legs and water) sprags in accordance with specified criteria 2. Ensure shear shafts available RESPONSIBILITIES 3. Ensure TTT ram start operational 1. Observe for changing conditions and 1. Inform control room operator of 1. Monitor and report chock and SIM 1. Inform Conrol Room Operator of Face action TARP condition of yellow affected areas clearance and convergence in yielding condition red areas Supervisor 2. Record face conditions on shift report and 2. Continual monitoring of affected areas zone 2. Ensure shearer is on tailgate side of identify all TARP triggered zones, yield or when mining within them 2. Inform control room operator of cavity during chocking and that personnel isolated positive set 3. Communicate conditions to oncoming condition orange affected areas are operating from a safe position 3. Monitor leg pressures and emulsion tank Face Supervisor 3. Continuously monitor affected area 3. Ensure 5 competent operators are levels whilst cutting in that zone available for production 4. Ensure TARP standards are being 4. Communicate conditions to on coming 4. Continuously monitor affected area followed Face Supervisor whilst cutting in that zone 5. Communicate conditions to on coming Face Supervisor 1. Monitor chock pressures and emulsion 1. Note changed conditions on shift report 1. Note changed conditions on shift report 1. Note changed conditions on shift report Control Room tank levels 2. Inform shift supervisor of changed 2. Inform Longwall Coordinator and Shift 2. Inform Longwall Coordinator, Shift Operator 2. Communicate irregularities in operating conditions Supervisor of changes in conditions Supervisor, Longwall Superintendant, system to face supervisor Geotechnical Engineer and Mine Manager 1. Provide support to face supervisor 1. Inspect area during shift 1. Inspect area ASAP 1. Inspect area immediately Shift 2. Communicate shiftly plan 2. Inform Longwall Superintendant, 2. Report conditions to Longwall Supervisor Longwall Coordinator and Geotechnical Superintendant and Geotechnical Engineer Engineer of conditions ASAP Geologist 1. Map the longwall face once per week 1. Map face daily 1. Map face daily 1. Routine chock pressure and convergence 1. Review Hazard Plan with Longwall 1. Inspect area ASAP 1. Visit affected area immediately monitoring Coordinator 2.Conduct daily inspection until conditions Geotechnical 2. Interpret and issue Hazard Plans 2. If conditions continue for longer than 2 improve Engineer informing Longwall Superintendant of shifts conduct an inspection during the potential hazards following shift 1. Ensure a leg and sprag audit is conducted 1. Review Hazard Plan with Geotechnical 1. Inspect area as soon as possible 1. Visit affected area immediately prior to maintenance shift Engineer 2. Audit and monitor longwall standards 2. If conditions continue for longer than 2 Longwall shifts, conduct an inspection during the Coordinator following shift 3. Inform Mine Manager of condition yellow if prevailing for longer than two shifts 1. Participate in the weekly Strata Control 1. Arrange audit of emergency onsite 1. Inspect area as soon as possible 1. Vist affected area immediately Review recovery equipment 2. Form interim plan with Longwall 2. Form Strata Management Team Coordinator and Geotechnical Engineer inclusing the Geotechnical Engineer and Longwall 3. Arrange availability of specialist Longwall Coordinator as a minimum. Superintendant contractors 3. Mobilise required specialist contractors 4. Inform Mine Manager of conditions and 4. Inform Mine Manager of conditions actions 1. Approve TARP 1. Approve Strata Management Team plan Mine Manager 2. Approve Hazard Plans of acton 2. Inform Senior Site Manager Appendix 17: An Example of a Change Management Policy Pertaining to Ground Engineering

Change Management Policy (iv) Support plans and support rules (e.g. and Process Geotechnical changing bolt density or placement) Assessment (b) Procedures that may impact on ground support (c) Major variation of the mine plan (e.g. chang- Introduction ing roadway orientation, gateroad pillar size) (d) Minor variations to mine plan (e.g. drivage It is a requirement that, as part of the company’s dimensions or sequence) change management process, geotechnical (e) Introduction of technical advances (e.g. new assessment shall be undertaken during modiﬁca- products, installation methods) tion to the mine operation or design. (f) Different geotechnical assessment techniques and methods (e.g. new software or criteria for decision making). Aim All persons who have the authority to approve The aim is to set the guidelines for the process of such changes to mine operations must ensure that investigating the geological and geotechnical any geotechnical impact is assessed. impact of changing any aspects of the mine operation. References or Related Documents Scope • Corporate Fatal Risk Control Procedures Potential changes to mine design or operation • Geotechnical Risk Assessment Process (Corpo- that may require assessment for geotechnical rate Standard Management Procedure No. ****) impact include: • Risk Assessment Procedure (Corporate Standard Management Procedure No. ****) (a) Ground support system • Mine Planning Management Procedure (Corpo- (i) Equipment used in ground support rate Standard Management Procedure No ****) (e.g. different continuous miner) (ii) Materials used in ground support (e.g. an alternative product, material Verification and Auditing Guidelines or design) (iii) Installation methods (e.g. sequence of The veriﬁcation that requirements of this proce- installation) dure have been carried out will be evidenced by:

# Springer International Publishing Switzerland 2016 641 J.M. Galvin, Ground Engineering - Principles and Practices for Underground Coal Mining, DOI 10.1007/978-3-319-25005-2 642 Appendix 17: An Example of a Change Management Policy Pertaining to Ground Engineering

(a) Geotechnical Engineer to keep “List of impact and report possible need of further Geotechnical Assessments Completed” for assessment to Coordinators. changes to the mine design or operation Mechanical and Electrical Engineer: recognise requiring a geotechnical assessment. that changes to the mine operation may have (b) Geotechnical assessment reports, where a geotechnical impact and seek an assessment relevant. from the Geotechnical Engineer. (c) Documented risk assessment, where required. Mining Crews: conﬁrm that changes to the mine operation are supported by a geotechnical assessment and a documented risk assessment Responsibilities (where required).

Mine Manager: confirm or sign-off that, where relevant, changes to any aspects of the mine Forms/Supporting Documents operation have been assessed for geotechnical impact. Ensure that a risk assessment has been • Maintain a “List of Geotechnical Assessments completed where required. Completed” – in response to changes to mine Geotechnical Engineer: to conduct an assessment design or operation. of the geotechnical impact, in terms of • Geotechnical Hazard Identification Checklist. hazards, risks and controls required. Initiate a risk assessment if the issue was not covered in a previous risk assessment, if it involves a Procedure physical change for the operations crews and if it is to be signed off by the Mine Manager. (a) Procedure Flowchart (attached) Maintain a list of changes assessed for geo- (b) Guidelines technical impact. Longwall, Development and Services The following guidelines indicate what level of Coordinators: to recognise that changes to geotechnical assessment may be required for the mine operation may have a geotechnical operational changes. For each modification, the impact and seek assessments from the Geo- risk ranking of identified hazards should indicate technical Engineer. what type of assessment of risk should be Undermanager: to recognise that changes to the completed – as per Corporate Risk Assessment mine operation may have a geotechnical Standard. Appendix 17: An Example of a Change Management Policy Pertaining to Ground Engineering 643

Geotechnical Risk Area of Modification Guidelines Assessment ** Report Assessment 1. Ground Support System i. Changes related to working panels may require a report and risk assessment. ii. Changes to be implemented in future panels must be included in the pre-mining risk assessment for that panel. Must meet the requirements of the support design • Equipment used in specification, Strata Management Plan and Fatal Risk Likely Yes ground support Procedures. Must meet the requirements of the support design Yes – if a • Materials used in specification, Strata Management Plan and Fatal Risk Yes physical ground support Procedures. Assess properties of new materials. New materials change may result in handling or installation modifications. • Installation methods Geotechnical assessment required for any modification. Yes Yes Yes – if a • Support Plans and Geotechnical assessment and report for changes such as significant Yes Support Rules support density, bolt placement, longer bolts etc physical change If outside area of Trigger Action Response Plan a full • Ground conditions Yes Yes geotechnical review and redesign is required 2. Procedures that may impact Assessment should be signed off Yes If required on ground support. Geotechnical Engineer notified of variation according to the 3. Variation of the Mine Plan If required If required “Mine Plan Management Procedure” (Doc No.****) Operations Co-ordinators to advise geotechnical engineer on 4. Minor operational variations changes such as mining sequence, roadway dimensions, Yes Possible to the Mine Plan adjustments to bolting cycle etc. 5. Introduction of technical A full geotechnical assessment of new methods, systems or Yes Yes advances technical improvements. In pre-mining 6. Different geotechnical Validate against existing methods. Yes risk assessment techniques assessment **Level of Risk Assessment to be determined using the Corporate Risk Assessment Standard

Procedure Review will also be reviewed at any time it is shown to be ineffective. The effectiveness of this procedure will be reviewed every 2 years by the Mine Manager. It 644 Appendix 17: An Example of a Change Management Policy Pertaining to Ground Engineering Appendix 18: An Example of a Ground Control Monitoring Plan Procedure

Ground Control Monitoring Plan Aim Procedure This procedure sets the guidelines for establishing a comprehensive monitoring plan Note for all aspects of ground control. This example of a Ground Control Monitoring Plan Procedure is presented Scope to illustrate the concepts associated with such a plan. It is not endorsed as being A monitoring plan is to be developed by the completely robust or universally Geotechnical Engineer for each mining panel. It applicable. may also apply to site-speciﬁc support design (e.g. drivehead installation sites etc.). Table A18.1 provides information on the application of monitoring with respect to: Introduction (a) Timing Legislation, company policies and standards and (b) Nature of the monitoring the Ground Control Management Plan have par- (c) Allocation of responsibility ticular monitoring requirements. (d) Nature of reporting This procedure provides guidelines for establishing the monitoring requirements for 5 different areas of ground control management. References or Related Documents These areas are: • Legislative requirements • Company policies and standards (a) Ground control monitoring for each panel. • Procedure for Ground Control Monitoring – This principally covers ground deformation Part 2 – comparing actual and expected. (b) Monitoring the quality of ground support installation. Training (c) Monitoring ground support equipment (d) Monitoring quality control of ground sup- Training for monitoring according to the TARP port materials will be provided to mining crews at the com- (e) Assessment of monitoring data. mencement of each mining panel.

# Springer International Publishing Switzerland 2016 645 J.M. Galvin, Ground Engineering - Principles and Practices for Underground Coal Mining, DOI 10.1007/978-3-319-25005-2 646 Appendix 18: An Example of a Ground Control Monitoring Plan Procedure

Table A18.1 Schedule for monitoring ground support requirements Ground control & displacement Ground support Ground support Ground support Assessment monitoring installation quality equipment materials of monitoring Shift/ Deputies and Deputies and Mech Eng, Deputies and Deputies: Daily Undermanagers: Undermanagers: Deputies and Undermanagers: Undermanagers: Inspections Inspections Inspections Inspections Observe, read and report as required Shift reports Shift reports Shift reports Shift reports Assess against trigger levels Weekly Geotechnical Geotechnical engineer: Geotechnical Geotechnical Geotechnical engineer: engineer: engineer: engineer: Review Review Review Review Database up-to-date Report by Report by exception Report by Report by Report by exception exception exception exception Monthly Geotechnical Geotechnical engineer: Geotechnical Geotechnical Geotechnical engineer: engineer: engineer: engineer: Maintain Check bolt/support Verify Receive batch Conﬁrm monitoring installation process inspections test results support schedules and tests done from design suppliers Report by exception Report by Report by Prepare exception exception monthly report 12 Geotechnical Geotechnical engineer: Geotechnical Geotechnical monthly engineer: engineer: engineer: Arrange audit Check entire mine site Check status Audit of procedures strata support process of testing checklist for from supply of system and suppliers materials to installation equipment issues Prepare audit Report Report Arrange report independent tests of materials Report A monthly status report on all monitoring is required from the Geotechnical Engineer

The Undermanagers and Geotechnical Engi- will also be reviewed at any time it is shown to be neer will be trained in their monitoring responsi- ineffective. bilities during induction; monitoring will be part of their role description. Procedure – The Panel Monitoring Plan

Procedure Review (a) Aim Provide guidelines for writing and planning The effectiveness of this procedure will be a speciﬁc monitoring plan for each panel. reviewed each 2 years by the Mine Manager. It (b) Veriﬁcation and Auditing Guidelines Appendix 18: An Example of a Ground Control Monitoring Plan Procedure 647

(i) The verification that requirements of also observe visual deformation of this procedure have been carried out ground conditions and support. will be evidenced by: (ii) Monitoring requirements should be (ii) Monitoring that is specified in each based on the expected or known geo- TARP is supported by a documented technical variation in each panel. For Monitoring Plan. example, variations in geology, geo- (iii) Monitoring reports are provided as technical properties, and changes in required by TARP. ground support may define a geotech- (iv) Monitoring results are available on site nical domain. Different levels of con- (underground) with suitable monitor- fidence in the knowledge of, or ing tools (Tell Tales and Gels). potential impact of, any of these (v) Monitoring database is up-to-date. should be considered. Note: System Auditor would audit (iii) Monitoring generally should focus on items (a) and (d); Undermanager to providing data to assess changing audit items (b) (shiftly) and conditions or changed ground (c) (weekly). support. (c) Responsibilities (iv) Monitoring requirements for any Geotechnical Engineer: to provide a moni- geotechnical domain should define: toring plan for each TARP, a maintenance 1. type of instrument, or type of schedule for monitoring apparatus, and monitoring complete their own tasks within the moni- 2. location toring schedule. 3. reading frequency Undermanager: to audit the shift reports for 4. reporting methods ground control information, and confirm 5. geotechnical mapping activities that monitoring apparatus are active and 6. responsibility for inspection, testing, monitoring results are available on site. installation, reading and reporting. Mining Crews: to monitor and report (v) Monitoring requirements are gener- ground conditions according to the TARP. ally included in the TARP for devel- (d) Forms/Supporting Documents opment, longwall or outbye roadway (i) Monitoring Plan (report) areas. They are linked to the expected (ii) Monitoring result sheets (may be part geotechnical conditions: of shift report) 1. trigger levels (for example, dis- (iii) Monitoring schedule (may be on placement rate, total displacement TARP) and longwall acceleration (iv) Maintenance schedule for monitoring position). apparatus 2. visual signs. (v) Mine plan with monitoring points and (vi) Specific monitoring instructions may status showing if active or inactive be issued, in addition to those (e) Standards included in the TARP. The following standards apply to the devel- (vii) A mine plan should be maintained by opment of the panel ground control moni- the Geotechnical Engineer that shows toring plan: the location and status of each moni- (i) Ground control monitoring will mea- toring zone and each monitoring sure the amount and rate of ground apparatus. movement at both unique (geotechni- (viii) Each monitoring apparatus cal) sites, and appropriate representa- (of appropriate type) is to be tive sites in a mining panel. It will maintained so that: 648 Appendix 18: An Example of a Ground Control Monitoring Plan Procedure

1. Inactive monitoring points are (iv) Schedule of Ground Support removed or tagged. Materials, Suppliers, Contacts etc. – 2. Damaged monitoring points are Appendix 2 replaced if still required. (v) Installation testing procedures 3. Monitoring data is recorded and (e) Monitoring Schedule maintained at the site to allow The schedule for monitoring ground support persons to immediately assess installation quality is: ground movement status. (i) Shiftly and Daily inspections by 4. A maintenance schedule is used to mining crews and statutory officials. confirm that monitoring apparatus Inspect compliance with the Support are “active”. Rules and TARPs. (ii) Weekly: the Geotechnical Engineer inspects each working area and reports Procedure – Monitoring the Quality by exception. Inspect compliance with of Ground Support Installation the Support Rules and TARPs. (iii) Monthly: the ground support installa- (a) Aim tion process is audited by checklist. This procedure is concerned with verifying (iv) 12 Monthly: a full audit of the ground that the systems, procedures, training, support installation process equipment and methods used result in the (f) Standards for Audit effective installation of ground support (i) Shiftly and Daily materials. The specification of ground support (b) Verification and Auditing Guidelines requirements are provided in the Sup- The verification that requirements of this port Rules, Support Plans, and TARP. procedure have been carried out will be Items that might be included in moni- evidenced by: toring ground support installation are: (i) Shift reports that note compliance & 1. Compliance with Support non compliance with the Support Rules etc. Rules, Support Plans and TARP. 2. Bolt spacing, row spacing (ii) Report by the Geotechnical Engineer as 3. Position of bolts, mesh required. This includes a regular status 4. Distance from last support to face report to the Strata Management Team. 5. Bolt tail length (c) Responsibilities 6. Spin times Geotechnical Engineer: this role has the 7. Bolt encapsulation. responsibility to co-ordinate the monthly 8. The monitoring is reported in shift auditing of ground support installation qual- reports. ity. Reports of each audit will be kept and (ii) Weekly reported to the Strata Management Team Each week the Geotechnical Engineer meetings. The Geotechnical Engineer is will inspect working panels for com- responsible for co-ordination of any pliance to support rules, support plans required corrective action. and TARPs. This will also include (d) Forms and Supporting Documents assessment of information in shift (i) Support Rules, Support Plans and reports reported by exception. TARPs (iii) Monthly (ii) Mine plan with monitoring points and Each month the Geotechnical Engi- their status neer shall complete an audit of a (iii) Checklists for Monthly Audits – panel to check the bolt installation pro- Appendix 1 cess and check that the equipment Appendix 18: An Example of a Ground Control Monitoring Plan Procedure 649

being used is running to correct 4. Transport underground specifications. This audit may be 5. Storage underground complemented by supplier audits or 6. Pull out tests checks. All support types in the panel 7. Drill steel length should be audited. Audit to include: 8. Position of installed bolts versus 1. Bolt/support type in use approved pattern 2. Crew on shift 9. Maintenance of bolting equipment. 3. Other installation hardware (mesh, 10. Use of testing procedures straps, plates) (g) Reporting and Corrective Action 4. Batch numbers Problems with support installations 5. Chemical type observed on shift are reported in shift 6. Drill bit size reports. Corrective actions are taken at the 7. Resulting hole diameter time, TARPs may be used, or work stopped 8. Hole length until the problem is resolved. 9. Spin and hold times The Geotechnical Engineer is to report 10. Encapsulation length in hole monthly on the quality of support installa- 11. Torque settings on rig tion as required and on the monitoring 12. Bolt torque. results. The Geotechnical Engineer is (iv) 12 Monthly responsible for co-ordination of any The purpose of this audit is to check required corrective action. the entire strata support process from supply of the support materials to the completion of the installation underground. These audits are to be carried Procedure – Monitoring Ground out by a team comprising at least 2 peo- Support Equipment ple, one of whom will be the Geotech- nical Engineer. The other person(s) on (a) Aim this team (nominated by the Geotech- To provide communication if defective nical Engineer), will have expertise in equipment is involved with the ground sup- a particular area of the strata support port process to allow correction and assess- process, such as, ment of potential impact. 1. Production manager (b) Verification and Auditing Guidelines 2. Team leader The verification that requirements of this 3. Operator procedure have been carried out will be 4. Consumables supplier evidenced by: 5. Mechanical engineer or tradesman (i) Maintenance reports. 6. Geotechnical expert (ii) Monthly monitoring report by the In addition to the items checked in Geotechnical Engineer to include “by daily, weekly and monthly audits the exception” reports of defective equip- following are noted in 12 monthly ment used for ground control. audits: (iii) 12 monthly audit reports. 1. Storage of consumables on surface (c) Responsibilities (a) Stock Mechanical Engineer: is responsible for the (b) Condition maintenance programs and maintenance (c) Use by dates schedule for equipment, including ground 2. Bolt storage support equipment. Ground Support Equip- 3. Resin storage ment that is operating out of specification 650 Appendix 18: An Example of a Ground Control Monitoring Plan Procedure

should be notified to the Process The Geotechnical Engineer monitors results Co-ordinator and the Geotechnical Engi- to confirm the integrity of ground support. neer to judge its impact on the effectiveness Consequently reports that include the status of ground support. of ground support equipment is reported by Geotechnical Engineer: To maintain a exception. Monthly status reviews are checklist of the ground support equipment reported by exception and 12 monthly sys- in use. To investigate “by exception” tem audits reports are completed. Reports reports of defective ground support equip- are to be made to the Strata Management ment. Assess the impact of equipment not Team. Immediate corrective action is operating to standard. Reports are to be directed by the TARP. The Mechanical completed as required. Engineer is responsible for co-ordination (d) Forms and Supporting Documents of any required corrective action. Checklist of Ground Support Equipment and Maintenance Schedule – Appendix 3. (e) Monitoring Standards Procedure – Monitoring Quality (i) Shiftly/Daily/Weekly of Ground Support Materials A maintenance schedule is available on ground support installation equip- (a) Aim ment, and longwall supports. Inspections made by tradesmen/ To provide methods for confirming that the engineers according to the inspection ground support materials, as they are sup- schedule. Mechanical Engineer to plied to the mine, fit the specifications notify Geotechnical Engineer if required in the ground support design. ground support equipment is not (b) Verification and Auditing Guidelines operating to specification. The verification that requirements of this (ii) Geotechnical Engineer to have a procedure have been carried out will be checklist of such equipment and main- evidenced by: tenance schedule. Refer to (i) Test reports from Suppliers Appendix 3. (ii) Monthly monitoring checklist by the (iii) Weekly Geotechnical Engineer The Geotechnical Engineer to review (iii) 12 Monthly monitoring report by the impact of equipment not operating to Geotechnical Engineer. specification (c) Responsibilities (iv) Monthly Geotechnical Engineer: to co-ordinate the The Geotechnical Engineer reviews monitoring program of ground support the status of ground support equip- materials supplied to the Mine. Reports ment. Follow up on reported defective shall be supplied to the Strata Management equipment and progress or corrective Team for: action. Report by exception. (i) monthly test reports are received and (v) 12 Monthly accepted, or rejected; and Audit status of inspection system, (ii) following 12 monthly audits. equipment issues and corrective (d) Forms and Supporting Documents action. Report audit findings. • List of ground support suppliers, contact (f) Reporting and Corrective Action details, materials and manufacturers The maintenance and inspection system will materials specifications. Appendix 2 report and schedule corrective action for • Current ground support materials equipment. specifications – Appendix 4 Appendix 18: An Example of a Ground Control Monitoring Plan Procedure 651

• Monthly Test Checklist for each Sup- This will include: plier – Appendix 5 1. Review the Suppliers current • 12 Monthly Test Checklist for each Sup- materials specifications, compare plier – Appendix 6 with contract or supply agreement. • Test Procedures – Appendix 7 2. Review the Mines current support (e) Monitoring Schedule design specifications The monitoring schedule is as follows: 3. Review the Suppliers testing proce- 1. Shiftly, daily and weekly. Reports by dure to confirm product exception from use and installation of specifications. materials. 4. Testing an example of each ground 2. Monthly: Provision and review of Sup- support apparatus to confirm that it plier test results for batches delivered meets Suppliers specifications. to site. 5. Review manufacturing quality con- 3. 12 Monthly: Detailed review of part of trol system – confirm that it is able each suppliers quality control system to supply materials to specification. including visits to suppliers sites. Understand the criteria used for Includes testing of materials. triggering rejection of product. (f) Monitoring Standards 6. Review Suppliers installation pro- (i) Shiftly/Daily/Weekly cedure – ensure it is included in During the handling, storage and mine procedures installation of ground support 7. Review training information sup- materials any abnormality to materials plied by Supplier should be recorded on shift reports. 8. Review supply system to mine. Suppliers are to be notified if materials Facilitate this by using a 12 Monthly are being supplied contrary to normal Test Checklist (Appendix 5) that specification. includes all ground support items Such items may include: from all Suppliers. 1. Different shape, size, or design (g) Reporting and Corrective Action 2. Different handling arrangements, or Geotechnical Engineer should report packaging monthly on the quality of materials deliv- 3. Different installation behaviour ered to the mine site during the last month if 4. Materials not “fit-for-purpose” they are out of specification. If materials are (ii) Monthly found to be out of specification the Geotech- Geotechnical Engineer to receive nical Engineer is to co-ordinate corrective manufacturing test reports on recent action. Each 12 months the Geotechnical batches delivered by the Supplier. Engineer will report the results of tests These should be reviewed and con- conducted on the ground support materials firmed to fit product specifications. and review of the Suppliers systems. Appendix 4 contains a checklist of quality reports which should be provided by the Supplier each month. Procedure – Assessment (iii) 12 Monthly of Monitoring Data Each 12 months a detailed audit program will be conducted on the (a) Aim Suppliers of all ground support To ensure that adequate assessment is made products. of the range of monitoring data collected. 652 Appendix 18: An Example of a Ground Control Monitoring Plan Procedure

Assessment is to provide a more detailed equipment and ground support understanding of the adequacy of the sup- materials should be utilised in a full port design. Different monitoring programs evaluation. aim to identify elements that may limit sup- (e) Reporting port effectiveness. The reporting requirements are detailed in (b) Verification and Auditing Guidelines the individual sections of this procedure. The verification that requirements of this Observations that are made on a routine procedure have been carried out will be shift or daily basis are reported in shift evidenced by: reports. The Geotechnical Engineer is (i) Updated monitoring database, includ- required to complete Monthly monitoring ing ground deformation monitoring reports. These monitoring reports should (ii) Monthly monitoring assessment report be a consolidated report for the reporting by the Geotechnical Engineer requirements outlined in the different (c) Responsibilities sections of this procedure. The Geotechnical Engineer is to evaluate the monitoring data, or co-ordinate expert assistance, to assess the effectiveness of the To complete this procedure the Appendices ground support system. need to be completed. They provide the (d) Standards of Assessment detail and substance of this procedure. (i) Shiftly/Daily Some liaison with suppliers will be required Monitoring data is collected and to complete Appendices 4, 5, 6, and 7. reported according to TARP or moni- Appendix 1: Checklist for Quality of Installation toring schedules controlled by the (Monthly) Geotechnical Engineer. In all cases Appendix 2: Schedule of Ground Support the results are tested against the Materials, Suppliers, Contact Details and TARP trigger levels. Manufacturers Materials Specifications (ii) Weekly Appendix 3: Checklist of Ground Control Instal- Monitoring data (ground displace- lation Equipment ment) is to be updated into the data Appendix 4: Current Ground Support Materials base at least weekly (having been Specifications. tested against the trigger levels on the Appendix 5: Supplier Quality Control Test day of reading). Report checklist (iii) Monthly Appendix 6: 12 Monthly Test Checklist for each A report is made that uses the available Supplier monitoring data to confirm the ground Appendix 7: Test Procedures for Ground Support support design. Monitoring data of Materials support installation, ground support Glossary of Terms

Abutment The zone of unmined rock Aquitard A body of rock which has a around the perimeter of an very low permeability, excavation. sufficient to significantly Act A law made by government. impede the transmission of Adit An entry driven in coal from a water. point where the coal seam ARMPS Analysis of Retreat Mining outcrops on the surface. Pillar Stability – an empirical AFC Armoured face conveyor – the pillar design methodology for chain conveyor installed on a pillar extraction mining. longwall face. Bag A colloquial term for ALARP As low as reasonably practical. ventilation sheeting, or brattice, used to partition a ALPS Analysis of Longwall Pillar roadway into an intake and a Stability – an empirical pillar return airway in order to direct design methodology for air to the coal face. longwall mining. Barring Down The act of prising loose pieces ALTS Analysis of Longwall Tailgate of rock from the roof and Serviceability – an empirical ribsides using a bar. Also pillar design methodology for referred to as ‘scaling down’. longwall mining. Baulk A wooden cross support with a Angle of Draw Defines the lateral extent of round (log), half-round (split mining-induced vertical log) or square (milled log) displacement on the surface. It cross-section. is the angle between two lines drawn from the edge of the Bedding Plane Shear Shear displacement along a mine workings, one a vertical bedding plane. line and the other a line to the Bi-directional The process of cutting the limit of vertical displacement cutting (Bi-di) longwall face to its full height on the surface. in a single pass of the shearer, Anisotropic Having different physical both from the maingate to the properties in different tailgate end and the tailgate to directions. An anisotropic the maingate end. material reacts differently in Bleeder Roadway A return airway that flanks a different directions to the same mining panel or a series of applied stress. mining panels for the purpose Aquiclude A body of rock which is of promoting a flow (bleed) of effectively impermeable. air through completed mine workings or goaves. Aquifer A permeable body of rock or regolith that both stores Boot-end The return roller end of a and transmits water (DoP conveyor belt. This is the 2010b). loading point in a production panel. (continued) (continued)

# Springer International Publishing Switzerland 2016 653 J.M. Galvin, Ground Engineering - Principles and Practices for Underground Coal Mining, DOI 10.1007/978-3-319-25005-2 654 Glossary of Terms

Bounce See ‘pressure bump’. profile of a natural or Brat See ‘scat’. man-made feature due to the Breaker Prop A prop, usually of timber, set impact of ground subsidence. for the purpose of breaking off Contact The plane or surface where two a fall of roof so as to prevent it different rock types meet. from overrunning into the Control A process, policy, device, workplace. practice or other action which Breaker Line A series of closely spaced rows modifies risk (ISO 31000 of breaker props which act as a 2009). A control can act to fulcrum to break off a fall of minimise negative risk or ground to prevent it from enhance positive opportunities. entering the workplace. Convergence The elastic rebound of the rock Typically, each row comprises mass into an excavation due to four to six breaker props, and removal of the virgin stresses each breaker line comprises from the surface of the two or three rows. excavation. At depth, the Brow The free, or cantilevered, edge magnitude of these stresses is of a step in the immediate roof such that the amount of resulting from a change in convergence cannot be mining horizon. May also be restrained by any practical referred to as a ‘lip’. form of artificial support Brownfield A geographical area in which (Jaeger and Cook 1979). there is a history of coal mining Cutter Another term for ‘guttering’. operations. Dip The angle at which a bed, Brush To increase the height of a stratum, or vein is inclined roadway by mining additional from the horizontal, measured material from the roof. perpendicular to the strike in Bump See ‘pressure bump’. the vertical plane. Burst See ‘pressure burst’. Also referred to as ‘hade’. Clacking A colloquial term that refers to Discontinuity A mechanical break in the the noise made by pressure fabric of the rock mass across relief valves when a powered which there may or may not support yields by releasing have been relative hydraulic fluid. displacement. Discontinuities Cleat A natural system of joints, or include fault planes, dykes, cleavage, within a coal seam. joints and bedding planes. Cleat is usually comprised of Dripper A joint plane, crack or drill two conjugate joint sets that are hole that drips water from the perpendicular or near roof of mine workings. perpendicular to stratification. Drummy Refers to a situation where one It is often confined to specific or more parting planes are coal plies. One joint set is present in the immediate roof usually more dominant and is strata. When struck with a referred to as face cleat; the steel, the strata sounds hollow other joint set is known as butt or ‘drummy’, as opposed to cleat. ‘ringing’ sharply. Competent Possessing sufficient Dyke A near vertical intrusion of knowledge, skill and igneous rock. experience to perform a Empirical Based on observation or function or task to an experiment. acceptable standard. Engineering Is the knowledge required and Consequence With respect to risk: Outcome the process applied to of an event affecting objectives conceive, design, make, build, (ISO 31000 2009). sustain, recycle or retire, – something of significant With respect to ground technical content for a subsidence: Any change in the specified purpose (Brown amenity, function or risk 2001a). (continued) (continued) Glossary of Terms 655

Event An occurrence or change of a Fracturing The formation of planes of particular set of circumstances separation in the rock material, (ISO 31000 2009). involving the breaking of Face break The snapping off of the bonds to form new surfaces. immediate roof at the face line The onset of fracture is not in longwall mining. necessarily synonymous with Fault Geological – A planar failure or with the attainment discontinuity between blocks of peak strength (Brady and of rock along which relative Brown 2006). shear displacement has Fretting The weathering/spalling/ occurred. disintegration of the ribs or Feather edge A term describing a type of roof in small pieces over a roof fall in which the roof falls period of time. as a thin wafer of rock, tapering Friable Easily broken. back from around 0.5–1.0 m in Gas Content The total desorbable volume of thickness to almost a razor gas contained in a known mass sharp edge in many cases. of coal at in-situ conditions These low angle shears are expressed in cubic metres per mostly associated with brittle tonne of coal at 20 C and strata, particularly sandstone 101.3 kPa. and conglomerate. Gate-end That area where the end of a Fender A long rectangular or slender longwall face intersects a web of coal separating a split gateroad. or lift from the goaf. Also Gateroad A roadway that ﬂanks the referred to as a ‘wing’ or a length of a longwall panel. ‘ ’ web in some situations. A GCMP Ground Control fender may or may not be Management Plan. subsequently partially or Geological Structure Refers to all natural planes totally extracted. of weakness in the rock Flit A term used to describe the mass that pre-date any process of relocating mobile mining activity and face equipment in an includes: joints, faults, underground coal mine. Most shears, bedding planes, often applied to the relocation, foliation and schistosity or tramming, of a continuous (NSW Dept. Mineral miner. Resources 2004). FMRS A Fletcher Mobile Roof – Support – a form of mobile Any disturbance whereby a roof support (MRS) coal seam is altered from its manufactured by Fletcher. original depositional state. Footwall The ﬂoor or base of a mine Geomechanics Is concerned with the physical opening. A footwall is not and mechanical properties and necessarily horizontal and is responses of soils and rocks distinguished from the hanging and their interactions with wall in that gravity acts to keep water and encompasses the the rock mass in position. In a subject of rock mechanics vein or bedded deposit, the (Brown 1998). footwall may comprise the top ‘ ’ surface of the rock stratum Gob Another term for goaf . underlying the deposit. Goaf An area in which mining has FOG Fall of ground. been completed and left in a partially or totally collapsed Fracture A natural or mining induced state or in an inadequately planar discontinuity between supported state to assure safe blocks of rock along which entry. An abandoned area. Also extremely little or no referred to as ‘gob’. discernible displacement has ‘ ’ occurred. Goaves Plural of goaf . (continued) (continued) 656 Glossary of Terms

Greasy back A slickensided surface within and pore space within the the immediate roof strata. window of interest. Greenfield A geographical area in which Hydromechanical Refers to the physical there is no previous history of Couple interaction between hydraulic coal mining operations. and mechanical processes. Grub To increase roadway height by Hypothesis A proposition or supposition going back and excavating made as a basis for reasoning more material from the floor. without reference to its truth. Grunch The process of shot-firing a Immediate Roof The nether roof of the mine coal face without first forming workings, defined to extend to a second free face by cutting a various heights above the mine slot in the face. workings roof, typically Ground Control A term used more commonly ranging from 10 m to ten times in mining than in the civil the mining height. construction industry and taken Inbye In a direction into the mine; in to mean the maintenance of the the direction of the stability of the rock around an working face. excavation and the more Inundation An inflow of fluid (in a gaseous general control of or liquid phase) or other displacements in the near-field material that develops over a of an excavation (Brady and period of time sufficient for it Brown,1993). not to present an immediate Guideline A principle, criterion or advice risk to health and safety. intended to set direction and Inrush A sudden and unplanned or standards. uncontrolled inflow into mine Guttering Shearing of the roof resulting workings of fluid (in a gaseous in a steep sided channel. or liquid phase) or other Usually occurs in the roof/rib material that has the potential corner section of a roadway. to result in unacceptable risk to Hanging wall The roof or top of a mine health and safety. opening. A hanging wall is not Intact Rock Rock which contains no necessarily horizontal and is discontinuities. distinguished from the footwall Joint A natural planar discontinuity in that it is undercut and, between blocks of rock along therefore, subject to material which little or no discernible being dislodged from it under displacement has occurred. the influence of gravity. In a Joints which are parallel in dip vein or bedded deposit, the and strike over a considerable hanging wall may comprise the area constitute a joint set. Two bottom surface of the rock or more joint sets that intersect stratum overlying the deposit. at more or less a constant angle Hang-up A situation in which the constitute a joint system. intended caving of the roof Isotropic Having the same physical strata has not occurred. properties and, therefore, the Hazard A source of potential harm or a same reaction to applied stress situation with a potential to in all directions. cause a loss (including to Lacing A pattern of cables strung people, property, the natural between tendons to aid in environment, business, or confining intermediate strata reputation). and screen supports. Also used Heterogeneous Of non-uniform composition. to provide a yielding capacity Homogenous Of uniform composition. in environments susceptible to Homogeneity is a measure of pressure bursts. the physical continuity of the Lagging Timber or steel used to infill rock mass based on the between roadway supports to distribution of discontinuities prevent the ingress of rock. (continued) (continued) Glossary of Terms 657

Laminations Layers within beds of strata. MRS Mobile roof support, based on Lift A slice of coal mined from a a powered longwall support. pillar for the purpose of MSHA (USA) Mine Safety and Health extracting the pillar. A lift may Administration. be mined from a heading, Muck (noun) – a pile of broken rock, cut-through or split. usually resulting from blasting Likelihood Chance of something or a fall of ground. happening (ISO 31000 2009). (verb) – the action of relocating – a pile of broken rock. Probability or frequency of an NCB (British) National Coal Board. event occurring. NIOSH (USA) National Institute of Lineament A topographic alignment of Occupational Safety and features that appears to be Health. structurally controlled. Also Normal Fault A fault plane in which the referred to as a ‘fracture trace’ direction of movement results or ‘photolineament’. in the extension of stratum Lip The edge of a brow, or step, in across the fault plane. the profile of the immediate Organisation A group of people and facilities roof. A lip may be the result of with an arrangement of a step change in mining responsibilities, authorities and horizon or a fall of ground. relationships Lithology The character of the rock (AS/NZS-4360:2004 2004). described in terms of its Orthogonal At right angles to. structure, colour, mineral Outburst A phenomenon in which a high composition, grain size, and concentration of gas usually arrangement of component accompanied by coal is parts (Gates et al. 2008). expelled from the roof, floor or Loss Any negative consequence. sides of a coal mining face. LTIFR Lost Time Injury Frequency Disturbance is confined to the Rate – lost time injuries per coal seam and occurs when the one million hours worked. pressure of the desorbed gas Massive In geology, the term is used to within the seam exceeds the describe a rock mass that has a confinement provided by the paucity of well developed rock mass, resulting in an bedding planes. inrush or inflow of material as MBLS Mobile Breaker Line Support, a fluidised bed propelled by the a form of mobile roof support desorbed gas. (MRS) developed by Voest In the USA, the term is Alpine. sometimes used to refer to a Mining Is that part of geomechanics pressure burst. Geomechanics (including rock mechanics) Outbye In a direction out of the mine; that is concerned with the in the direction of the surface. application of knowledge of Overburden A generic term encompassing the physical and mechanical all solid and liquid material behaviour of geological overlying a mine. materials (soils, rock and Overcast A construction at the water) to the investigation, intersection of two roadways in design, operation and an underground ventilation performance of mining circuit which permits intake air structures including in one roadway to cross over excavations (Brown 1998). return air in the other roadway. Monitor To check, supervise, observe Parallelepiped A polyhedron comprised of six critically or measure the faces that are parallelograms. progress of an activity, action Parting A mechanical weakness within or system on a regular basis in bedding comprised of a lamina order to identify change from or thin bed of weak material the performance levels which may vary in thickness required or expected from a fraction of a millimetre (AS/NZS-4360:2004 2004). to some tens of millimetres. (continued) (continued) 658 Glossary of Terms

The weak material promotes in ejection of material into the separation of the strata workplace. (adapted from Cook An event associated with the et al. 1974). dynamic release of energy – within the rock mass that is of An opening due to separation sufficient magnitude to between bedding planes. generate an audible signal; Permeability A measure of the rate at which ground vibration; and potential fluid can be transmitted for displacement of loose or through a body. fractured material into the mine workings. Also referred Piezometer A non-pumping well or to in the USA as a ‘bounce’. borehole, generally of a small diameter, used to measure the Pressure Burst Defined in this text as a elevation of the water table or pressure bump that results in potentiometric surface (DoP dynamic rock failure 2010b). (including coal) in the vicinity of a mining excavation, Pillar Point Created when a pillar is resulting in high velocity adjacent to extensive mined- expulsion of the failed material out goaf on two sides (NIOSH into the excavation. The energy 2010). Also referred to as an levels and associated velocities ‘arrow head’. are sufficiently high to result in Pillar Stripping The process of reducing the significant damage to, and even size of a pillar by mining lifts destruction of, conventional from its perimeter. Also rock mass support and ‘ ’ referred to as slabbing . reinforcement systems. Plunge The distance that a roadway is An explosive breaking of coal advanced between ground or rock in a mine due to ‘ ’ support cycles; the cut-out pressure; the sudden and distance. violent failure of overstressed Pocket A blind lift separated from an rock resulting in the adjacent lift by a narrow fender instantaneous release of large or web of coal. amounts of accumulated Policy A course or principle of action energy where coal or rock is or behaviour decided by suddenly expelled from failed government, management or pillars (Gates et al. 2008). individuals. Can also be referred to in the Pot Arse A block of roof material, often USA as ‘bump’ or as a dome shaped, that is defined by ‘bounce’. slickensided or smooth contact Primary Workings Workings driven in the process surfaces of negligible tensile of developing the main arteries strength. of a mine. Pozzolanic Possessing natural self- Principal Hazard A hazard with the potential to cementing properties. cause multiple fatalities. Pressure Bounce A heavy, sudden, often noisy Procedure A series of steps and actions blow or thump; sudden spalling carried out in a certain order or off to sides of ribs and pillars manner. due to excessive pressure; any Process A set of interrelated resources dull, hollow, or thumping and activities which transform sound produced by movement inputs into identifiable outputs. or fracturing of strata as a Pushout A USA term for a stook or result of mining operations. stump formed in the vicinity of Also known as a ‘bump’ (Gates an intersection when extracting et al. 2008). a coal pillar. Pressure Bump Defined in this text as a seismic Regolith The blanket of soil and loose event that can be felt by the rock fragments overlying human body but does not result (continued) (continued) Glossary of Terms 659

bedrock. It includes dust; soil; Risk Criteria Terms of reference against broken and weathered rock; which the significance of risk is and other related materials evaluated (ISO 31000 2009). (DoP 2010b). Risk Management The systematic application of Regulation Subordinate legislation in Process management policies, support of an Act. procedures and practices to the Reinforcement Measures which act from activities of communicating, within the rock mass to establishing the context, and improve the overall rock mass identifying, analysing, properties. Examples include evaluating, treating, rock bolts, cable bolts and monitoring and reviewing risk strata binders (adapted from (ISO 31000 2009). Brown 1998). Risk Treatment The process to modify risk Residual Risk The risk remaining after risk (ISO 31000 2009). treatment (ISO 31000 2009). Rock Mass The sum total of the rock as it Retreat Mining A mining process in which exists in situ. This includes secondary extraction is intact rock material, undertaken as mining groundwater, fractures, faults, operations retreat out of a panel dykes and other planes of under the protection of the weakness. primary workings. Rock Mechanics Is the theoretical and applied Reverse Fault A fault plane in which the science of the mechanical direction of movement results behaviour of rock and rock in compression, or overriding, masses; it is that branch of of stratum across the fault mechanics concerned with the plane. response of rock and rock masses to the force fields of Review Activity undertaken to their physical environment determine the suitability, (Brady and Brown 2006, as adequacy and effectiveness of offered by the US National the subject matter to achieve Committee on Rock established objectives (ISO Mechanics). 31000 2009). Run-out A long split driven from the Rib Side or sidewall of a coal pillar. main panel development to the Ride Down dip shear displacement flanks of a pillar extraction of the roof of mine workings panel. relative to the floor. Scaling Down The act of prising loose pieces Rider A thin seam of coal overlying a of rock from the roof and main coal seam. ribsides using a bar. Also Rill The action of solid material referred to as ‘barring down’. flowing under gravity. Scat Small pieces of rock which fall Risk A combined measure of the from the surface of an consequences of an event and excavation. Also referred to as the likelihood that the event ‘brat’. will occur. Risk may have Seal A substantial stopping or positive or negative barrier constructed in a consequences. roadway to prevent or retain – fluid flow. The effect that uncertainty has Serviceability Level of suitability, usefulness, on an organisation’s objectives and effectiveness in fulfilling (ISO 31000 2009). required functions. Risk Analysis A process to comprehend the Sequence The order in which pillars are nature of risk and to determine developed and/or lifted off. the level of risk (ISO SFARP So far as is reasonably 31000 2009). practical Risk Assessment The overall process of risk Shaft A vertical or near vertical identification, risk analysis and connection between the surface risk evaluation (ISO and the mining horizon. 31000 2009). (continued) (continued) 660 Glossary of Terms

Shotcrete A mortar or concrete mix Spile (noun) – A bar or tube that is sprayed onto a surface at high driven in over the top of weak pressure using compressed air. or fallen ground. Shunt (noun) – A temporary parking – bay to permit one vehicle to (verb) – The process of pass another approaching from driving a series of parallel the opposite direction. spiles in close proximity to – each other over the top of (verb) – The act of moving into weakorfallengroundsoasto a passing bay to permit another form an artiﬁcial roof, or vehicle to pass. ‘verandah,’ and then Sill A laterally extensive intrusion incrementally providing of igneous material. support to this verandah as the material beneath it is Slabbing See ‘pillar stripping’. removed. In the case of a fall Slickenside A smooth, slippery sliding of ground, the verandah is plane within the rock mass. usually progressively Slip A well developed planar joint supported by cross supports in a coal pillar. Slips are noted set on heavy legs. Where the for their propensity to result in material is yet to fall, tendon a rib fall. support may be utilised in Snook A South African term for place of, or as well as, cross ‘stook’. supports and legs. Soft In relation to strata, refers to Split A roadway developed within a materials that are more soil like pillar to divide it into smaller and homogenous with little in portions. Also referred to as a the way of defects, so that the pocket in some situations. low uniaxial compressive Sprag A support set against the face strength (UCS) of these of a coal rib or sidewall to materials is due to the low retain the face of the sidewall strength of the intact material. in place. Historically, sprags – comprised short props set In relation to load and horizontally between the displacement, refers to a sidewall and vertical props. structure that has a low Most sprags now comprise stiffness (such that a small some form of hydraulically increment in load results in a activated steel face plate. large increment in Squeeze A controlled pillar system displacement). failure. Also referred to as a Spalling In rock mechanics and hard ‘ride’ or ‘pillar run’. rock mining, the term describes Standard Operating A documented way of working stress-induced fracturing at the Procedure or an arrangement of facilities boundary of an excavation in for the purpose of achieving an regions of maximum tangential acceptable level of risk. stress. Strata Control A term widely used in the – mining industry before the In coal mining, the term is used development of the terms in a more general sense to ‘geomechanics’, ‘rock encompass all unravelling and mechanics’ and ‘mining falling of material from the geomechanics’. It is still used sides of a coal pillar. in the coal mining industry to ‘ Span The shortest distance between mean the control and two abutments. prediction of strata behaviour (continued) (continued) Glossary of Terms 661

during development and Technology An enabling package of extraction operations’ knowledge, devices, systems, (Brown 1998). processes, and other Stochastic Process of determining technologies, created for a likelihood on the basis of a specific purpose (Brown 2001a). random distribution of Thixotropic A material that exists in a gel probabilities. state under static conditions but Stook An term used in Australian becomes fluid when shaken, pillar extraction operations to stirred or otherwise stressed. describe a remnant portion of a Threat A means by which a hazard can pillar. Referred to as a ‘snook’ materialise. in South Africa and as a ‘stump’ Thrust Fault A reverse fault that dips at less or a ‘pushout’ in the USA. than 45. Stooping Another term for pillar Top Hat A cross support utilized in coal extraction. mining that comprises a rolled Stopping A wall or barricade built across steel channel of typically a roadway to separate air 4–10 mm wall thickness that courses in a mine. has the cross-section of a top Strike The direction of a line that hat. The deep throat imparts a defines the intersection of a high moment of inertia relative rock bed with a horizontal to the weight of the beam. plane. Transversely Having the same physical Strike-slip Fault A fault plane in which the Isotropic properties and, therefore, the direction of movement is along same reaction to stress in two the strike of the fault. orthogonal directions but not in the third direction. Stripping See ‘pillar stripping’. Trigger Risk Management – a Strong In respect of rock, typically predetermined type or regarded as material with a magnitude of behaviour uniaxial compressive strength prompting intervention. >40–50 MPa. – Structure See ‘geological structure’. Physics – a threshold value Stump A USA term for a stook. which, if exceeded, results in Support The application of a reactive instability that produces a force at the face of an sudden change in system excavation. Examples include properties. timber props, shotcrete and Trigger Action A plan designed to prevent a backfill (adapted from Response Plan threat from escalating by Brown 1998). (TARP) identifying potential Surge The process of operating two precursors, or triggers, to the shuttle cars in series, whereby threat event, assigning a one shuttle car transfers its load hierarchy of alarms, or trigger to another at some point along levels, to each potential the wheeling route between the precursor, and specifying coal face and the panel responses for each trigger conveyor belt. level. Swilley A localised depression in the Unravelling Progressive disintegration of working floor of a coal seam. the strata between ground Often associated with weak support elements. Also referred ground conditions. to as ‘ravelling’. Uni-directional The process of cutting the UNSW University of New South cutting (Uni-di) longwall face to its full height Wales (Sydney, Australia). in two passes of the shearer, Verandah A false roof constructed to with the first pass taking a cut support overlying weak strata. from the upper portion of the coal face and the return pass Water Crack A wet or water bearing joint cutting out the remainder of plane in the roof of coal mine the face. workings. A water crack may dry up over time but still be Tabular Bedded and laterally extensive. detectable due to staining. TARP Trigger Action Response Plan. (continued) (continued) 662 Glossary of Terms

Weak In relation to strata, refers to References materials that are not necessarily homogenous and AS/NZS-4360:2004. (2004). Risk management. Canberra: have a low strength, typically Standards Australia/Standards New Zealand. in a uniaxial compressive Brady, B. H. G., & Brown, E. T. (1993). Rock mechanics strength range of 0.5–10 MPa, for underground mining (2nd ed.). London: Chapman as a result of the very low & Hall. strength of the intact material Brady, B. H. G., & Brown, E. T. (2006). Rock mechanics and/or because of a signiﬁcant for underground mining (3rd ed.). Dordrecht: density of lower strength Springer. defects. Brown, E. T. (1998, July 14–17). Ground control for Web A thin fender of coal left underground excavations – Achievements and between two lifts, usually as a challenges. Paper presented at the international con- temporary support measure. ference on geomechanics/ground control in mining Portions of a web may be and underground construction, Wollongong. extracted (pocketed) on retreat Brown, E. T. (2001a). From sordid toil to the digital age. out of a lift. 150 years of achievements in mining. Keynote Wheeling A term used to describe the Address. Royal School of Mines 150th Anniverary. conveying of coal by means of London: Imperial College. mobile vehicles from the DoP. (2010b). Wallarah 2 Coal Project – Planning Assess- working face to the panel ment Commission Report (pp. 314). Sydney: Depart- conveyor belt. ment of Planning, NSW Government. Wheeling Road Roadways used by mobile Gates, R. A., Gauna, M., Morley, T. A., O’Donnell, J. R., vehicles for conveying coal Smith, G. E., Watkins, T. R., Weaver, C. A., Zelanko, from the coal face to the panel J. C. (2008). Report of investigation. Fatal under- conveyor belt. ground coal burst accidents, August 6 and 16, 2007. Winded Coal Coal that has been destressed, Crandall Canyon Mine (pp. 472). Arlington: Mine usually as a result of failing. Safety and Health Administration. Windrow A pile of loose rock placed as a ISO 31000. (2009). Risk management – Principles and barrier down the sides or guidelines. Geneva: International Standards middle of a surface roadway. Organisation. – Jaeger, J. C., & Cook, N. G. W. (1979). Fundamentals of Loose rock material that spills rock mechanics (3rd ed.). London: Chapman and Hall. from the blade or shovel of NIOSH. (2010). Research report on the coal pillar recov- mining equipment such as ery under deep cover (pp. 82). bulldozers, graders and continuous miners or which is pushed up in front of the blade or shovel. Glossary of Symbols

Symbol Description Dimensions Symbol Description Dimensions 2 a An input parameter to Dimensionless cr Residual cohesion N/m 2 the Hoek-Brown failure c1 Cohesion of upper layer N/m criterion of soft ﬂoor material 2 2 A Area over which a force m c2 Cohesion of lower layer N/m acts of soft ﬂoor material Cross-sectional area C Compression Dimensionless 2 Ac Tributary area of a pillar m Cα Secondary compression Dimensionless (in plan view) index

Ai Area beneath a stress or N Cc Compressibility index Dimensionless pressure profile (which Cp Circumference of a pillar m equates to total force) 2 2 Cv Coefficient of m /s Am Area of workings m consolidation extracted (exposed roof C Pillar centre distance m area) 1 2 parallel to shortest pillar Ap Cross-sectional area of a m side pillar (in plan view) w1 +b1/sin A1,A2, Area beneath a stress or N θ ¼ w1 +b1cosec θ pressure profile (which C Pillar centre distance m equates to total force) 2 parallel to longest pillar b Beam width m side Bord or roadway width m w2 +b2/sin Aperture of a rock m θ ¼ w2 +b2cosec θ fracture d Distance m b1 Bord or roadway width m Specimen diameter m at right angles to longest Depth of a footing m pillar side beneath the surface b Bord or roadway width m 2 d Diameter of a tendon m at right angles to T shortest pillar side D Lateral extent of side m abutment zone B Footing diameter or m width Dd Depth to base of a m dolerite sill Bi Area beneath a stress or N pressure profile (which e Areal extraction, m equates to total force) expressed as a fraction c Cohesion N/m2 Distance from neutral m axis to point of (eccentric) Distance from central m loading on a column axis about which bending occurs in a Pre-existing eccentricity Dimensionless column or beam in a column (continued) (continued)

# Springer International Publishing Switzerland 2016 663 J.M. Galvin, Ground Engineering - Principles and Practices for Underground Coal Mining, DOI 10.1007/978-3-319-25005-2 664 Glossary of Symbols

Symbol Description Dimensions Symbol Description Dimensions eo Void ratio Dimensionless Hf Head of fluid acting at m E Modulus N/m2 roof level or height of 2 fluid above roof level Ec Elastic modulus of coal N/m 2 Hsolid rock Solid rock head cover to m Eeq-n Equivalent elastic N/m modulus normal to working horizon bedding i A friction angle that Degrees 2 accounts for asperities Eeq-p Equivalent elastic N/m modulus parallel to on a fracture surface, or bedding angle of saw tooth 2 asperity faces Ef Modulus of deformation N/m 4 of backfill or caved I Second moment of m material inertia 2 Ip A footing influence Dimensionless Eo Effective elastic N/m modulus of the factor overburden Ja Joint alteration number Dimensionless 2 Es Secant modulus N/m Jn Joint set number Dimensionless 2 Et Tangent modulus N/m Jr Joint roughness number Dimensionless 2 ET Elastic modulus of N/m Jw Joint water reduction Dimensionless tendon material factor 2 Eti Initial tangential N/m JRC Joint roughness Dimensionless modulus of backfill coefficient material JCS Joint wall compressive N/m2 2 Eu Undrained modulus N/m strength f1 Moment arm distance to m k Stiffness N/m force F1 Horizontal to vertical Dimensionless f2 Moment arm distance to m stress ratio force F2 Bulking factor of caved Dimensionless F Force (driving or N strata reaction) An adjustment factor to Dimensionless

Fpt Pretension force applied N account for dimensions to a tendon of input parameters 2 FH Horizontal force N Permeability m

F1,F2 Driving forces N kbond Stiffness of N/m g Gravitational m/s2 encapsulating medium acceleration constant kf Stiffness of backfill or N/m 2 caved material Ge Shear modulus of N/m encapsulating grout ki Initial bulking factor Dimensionless GSI Geological Strength Dimensionless kt Tendon stiffness N/m 2 Index k1 Compressive strength of N/m h Specimen height m a reference cube of coal Mining height or pillar m used in linear pillar height strength formulae 2 k2 Strength of a reference N/m hc Height of caving m body of coal used in h Height of a reference m o power pillar strength body used in power formulae pillar strength formulae K Strength magnification Dimensionless factor due to H Depth of mining m confinement (measured to either top of seam or bottom of Effective length Dimensionless seam) coefficient for a column Length of drainage path m Hydraulic conductivity m/s or coefficient of H Height of complete m d permeability groundwater drainage (continued) (continued) Glossary of Symbols 665

Symbol Description Dimensions Symbol Description Dimensions

K1,K2, Proportionality factors Dimensionless Nq A bearing capacity Dimensionless K3,K4 associated with classical factor beam theory Nγ A bearing capacity Dimensionless formulations for factor various beam and p Hydrostatic stress N/m2 column loading Applied overburden N/m2 configurations and end stress constraints p A material constant N/m2 l Length of a fracture m c orthogonal to flow P Load applied axially to a N column lLT Load transfer distance m 2 along a tendon Ventilation fan pressure N/m L Length of a tendon m Pcr Critical axial load or N Euler critical load Length of a footing m P Average roof contact N/m2 L Effective length of a m Ra e pressure of a powered column or beam support canopy Lp Pillar load N 2 PFa Average floor contact N/m LP peak Peak load capacity of a N pressure of a powered tendon plate assembly support base Ls Total side abutment load N q Uniformly distributed N/m2 based on abutment angle load on a structure concept (beam, footing etc.) LT Tensile force generated N 2 qu Bearing capacity of a N/m in a tendon foundation LT peak Ultimate tensile N Q Fluid flow rate m3/s capacity of a tendon (ventilation air, LT yield Yield load of a tendon N groundwater etc.) Lup Load acting upwards on N r Correlation coefficient Dimensionless the roof of mine A dimensionless Dimensionless workings constant used in linear mb An input parameter to Dimensionless pillar strength formulae the Hoek-Brown failure Least radius of gyration m criterion for a column mε Strain magnification Dimensionless r1 Moment arm distance to m factor reaction force R1 2 mv Coefficient of volume m /N r2 Moment arm distance to m compressibility reaction force R2 M Moment couple or Nm r2 Coefficient of Dimensionless internal bending determination moment R Pillar width-to-height Dimensionless Mext External bending Nm ratio moment Spacing between rows m Mint Internal bending Nm of tendons moment Roadway (ventilation) Ns2/m8 n Number of data points Dimensionless resistance Number of tendons per Tendons/m2 Rmin Minimum pillar width- Dimensionless square metre to-height ratio (wmin/h) N Number of tendons per Dimensionless Ro The width-to-height Dimensionless row ratio at which a pillar Nc A bearing capacity Dimensionless is considered to be factor ‘squat’ (continued) (continued) 666 Glossary of Symbols

Symbol Description Dimensions Symbol Description Dimensions

Rl The width-to-height Dimensionless t100 Foundation layer m ratio at which thickness at end of rectangular pillar primary consolidation

strength beneﬁts ﬁrst Tx Time to reach x% s start to materialise consolidation

Ru The width-to-height Dimensionless TF(x) Time factor Dimensionless ratio at which associated with x% rectangular pillar consolidation strength beneﬁts are T Tension Dimensionless maximised Tf A tensile strength Dimensionless R1 Radius of curvature m reduction factor, Resultant force N typically in the range of R2 Radius of curvature m 10–30

Resultant force N T1 Time when secondary s s An input parameter to Dimensionless consolidation is the Hoek-Brown failure assumed to begin criterion T2 Time for which s Standard deviation Dimensionless secondary settlements s2 Variance or second Dimensionless are calculated moment TSF Tectonic Stress Factor Dimensionless S Span of a beam m or tectonic induced strain Span of an excavation m u Pore pressure N/m2 A fictitious balancing or N 2 stabilising force Hydrostatic pressure N/m U Potential energy J Sc A foundation Dimensionless engineering shape factor Uhi Inward deflection of the m abutments of a beam Se Elastic settlement m under the effect of a S Primary consolidation m p lateral load. settlement U Deflection at the m S A foundation Dimensionless vi q mid-span of a beam or engineering shape factor column due to the Ss Secondary consolidation m abutments deflecting settlement inwards by an amount S Ultimate tensile strength N/m2 t Uhi of a tendon Uxi Deflection of a beam or m Sγ A foundation Dimensionless column at any point x engineering shape factor along its axis t Thickness of a beam, m V Material volume m3 column or plate Pillar volume m3 Thickness of foundation m Transverse shear force N layer Vx Transverse horizontal m Width of tendon/width m surface displacement annulus Vy Longitudinal m td Thickness of a bridging m horizontal surface superincumbent strata displacement tp Thickness of parting m Vz Vertical surface m between mining horizon displacement and base of a dolerite sill Vz max Maximum vertical m t1 Thickness of upper layer m surface displacement of soft floor material w Specimen width m t Thickness of lower layer m 2 Pillar width m of soft floor material Width of a footing m (continued) (continued) Glossary of Symbols 667

Symbol Description Dimensions Symbol Description Dimensions 0 weff Effective width of a m z Deviation in a column m parallelepiped shaped α Angle of draw, Degrees pillar when equated to measured from the the strength of a square vertical pillar Angle of break, Degrees wmin Minimum pillar width m measured from the (normal to long side of vertical, of a detached ¼ θ pillar) w1 Sin roof block on a longwall wo Width of a reference m face body used in power The power to which the Dimensionless pillar strength formulae width parameter is w1 Length of shortest side m raised in power pillar of a pillar strength formulae

Length of shortest side m αu A pore pressure Dimensionless of a foundation reduction factor w2 Length of longest side of m β Angle of break or caving Degrees a pillar angle over the goaf Length of longest side of m measured from the a foundation horizontal (or mining W Width of an excavation m horizon) – rib to rib The power to which the Dimensionless Maximum weight of a N height parameter is detached block that a raised in power pillar longwall powered strength formulae 3 support can sustain γ Speciﬁc weight, or unit N/m without going into yield weight

Wc Critical panel width m Shear strain or Dimensionless 3 horizontal distortion We Strain energy per unit J/m γ 3 volume w Unit weight of water N/m δ Wo The overall extent m Deﬂection m (width) of a series of δb0 Deﬂection of a beam m adjacent mining panels when supported at its

Wp Overall width of a panel m mid-span of pillars δb Deflection of a beam m 3 W1 Stored elastic strain J/m that is not supported at energy resulting from an its mid-span application of a tendon δmax Maximum deflection m force, F ε Strain Dimensionless 3 W2 Stored elastic strain J/m A measure of the rate of Dimensionless energy resulting from an squat pillar strength application of a tendon increase once wm/h force, Fx exceeds Ro x An independent variable Dimensionless εa Axial strain Dimensionless x Mean x value, first Dimensionless εc Compressive strain Dimensionless moment or centre of εf Critical failure strain Dimensionless gravity ε th H Lateral pillar strain Dimensionless xi The i data value Dimensionless εl Lateral strain Dimensionless y A dependent variable Dimensionless εlp Lateral pillar strain Dimensionless y Mean y value Dimensionless εm Maximum strain that can Dimensionless z The normal distance m be developed in backfill from the neutral axis to a ε Tensile strain Dimensionless point, p. t (continued) (continued) 668 Glossary of Symbols

Symbol Description Dimensions Symbol Description Dimensions 2 εV Vertical pillar strain – Dimensionless σl Lateral stress N/m 2 ashfill research σmax comp Maximum compressive N/m θ Abutment angle, Degrees fibre stress in a beam, measured from the column or plate 2 vertical σmax ten Maximum tensile fibre N/m The smaller internal Degrees stress in a beam, column angle of a parallelepiped or plate θ 2 shaped pillar ( 90 ) σn Normal stress N/m λ 0 2 Slenderness ratio of a Dimensionless σ n Effective normal stress N/m column 2 σ0 Axial stress in a tendon N/m μ Coefficient of Dimensionless σ Vertical pillar stress – N/m2 ¼ ϕ p friction Tan( ) ashfill research μd Dynamic viscosity kg/ms 2 σps Pillar strength N/m μR Resin/rock coefficient of Dimensionless 2 σrr Radial stress N/m friction 2 σv Vertical stress N/m μ Tendon/resin coefficient Dimensionless T σ Vertical effective stress N/m2 of friction ve σ Vertical primitive stress N/m2 ν Poisson’s ratio Dimensionless vp σ Yield stress N/m2 ρ Density kg/m3 y σ Maximum, or major, N/m2 ρ Effective (overall) kg/m3 1 o principal stress density of the 2 overburden Triaxial strength N/m σ 2 ρ Density of fluid kg/m3 2 Intermediate principal N/m f stress σ Stress (including N/m2 σ 2 overburden stress) 3 Minimum, or minor, N/m principal stress σ0 Effective stress N/m2 Confining stress N/m2 σ Axial stress N/m2 a σ0 Maximum principal N/m2 2 1 σaps Average pillar stress N/m 2 effective stress at failure σ Abutment stress at N/m 0 ax σ Minimum principal N/m2 distance of x metres 3 effective stress at failure from the edge of an σ 2 excavation θθ Tangential stress N/m τ 2 σ Lateral ashfill pressure N/m2 Shear stress N/m A τ 2 σ Uniaxial compressive N/m2 max Maximum shear stress N/m c 2 stress τ(x) Shear stress at a distance N/m σ Uniaxial compressive N/m2 x along a tendon c50 τ 2 stress of a 50 mm c The cohesive N/m diameter specimen component of shear σ Intact compressive N/m2 resistance ci τ 2 strength f The frictional N/m 2 component of shear σf Fibre stress in a beam, N/m column or plate resistance τ 2 Backfill reaction stress N/m2 r Residual shear strength N/m τ 2 Confining pressure N/m2 T Total shear resistance N/m τ 2 developed by backfill or xz ave Average shear stress N/m caved material acting in z direction of 2 plane yz σh Horizontal stress N/m 2 ϕ Angle of friction Degrees σhp Horizontal primitive N/m stress Effective abutment Degrees 2 angle over the goaf, σips Induced average pillar N/m stress measured from the vertical (continued) (continued) Glossary of Symbols 669

Symbol Description Dimensions Symbol Description Dimensions

ϕb Base friction angle or Degrees ΔP Incremental axial force N angle of friction on a applied to a column 2 smooth surface Δσvi Induced vertical stress N/m À ϕ R Rl d Dynamic angle of Degrees Θ À Dimensionless ¼ ΘRu Rl friction o Θ ¼2w /(w +w) Dimensionless ϕr Residual friction angle Degrees o 2 1 2

ϕs Static angle of friction Degrees φ Angle through which the Degrees Symbols in Metric System end of a beam or column may rotate nano n 10À9 billionth Δ À d Displacement m micro μ 10 6 millionth Δ À h Change in pillar height m milli m 10 3 thousandth (pillar compression) or 100 (¼1 unit) change in mining height kilo k 103 thousand Head difference along a m 6 ﬂow path mega M 10 million 9 Δl Distance/dilation across m giga G 10 billion a parting place Distance between m measurements of head (continued) Index

A subsidence remediation Abermain Colliery, Australia, 215 sinkholes, 115 Abutment angle. See Caving surface cracks, 472 Acoustic emission, 26 Bayesian theory, 63 Adit, definition, 15 Bearing capacity. See also Appendix 4; Floor, heave Analysis techniques bulkhead perimeter, 489 analytical methods, 55 geologically structured areas, 295 empirical methods, 54 interburden in multiseam mining, 204 normalising data, 53 longwall mining numerical methods, 55 pre-driven roadway fender, 409–411 parametric analysis, 57 roof and floor at face, 204, 384, 391–392 probabilistic analysis, 59–64 roof and floor in gateroads, 371 sensitivity analysis, 57 through a fault, 507 statistical analysis, 59–64 pillar system foundations, 135–136, 141, 160, Angle of break. See Caving 165–169, 338, 370, 460 Angle of caving. See Caving tendon Angle of draw. See Subsidence, surface face plate assembly, 246 Angle of repose, 28 mechanical end anchor, 251 Angus Place Colliery, Australia, 236, 237, 264, 265, Bellbird Colliery, Australia, 215 304, 560 Bord and pillar mining Appin Colliery, Australia, 94, 97, 98, 189, cut and bolt, 17 202, 496 cut and flit, 17 Aquiclude zone, 429 first workings, 17 Austar Coal Mine, Australia, 372 hybrid pillars, 174 Auxetic, 26 irregular shaped pillars, 174 Awaba Colliery, Australia, 165, 166, 510 pillar pocketing, 174 pillar stripping, 174 B Bord, definition, 16 Backfill Bosjesspruit Colliery, South Africa, 405 bord and pillar workings Bow tie diagram. See Risk assessment improving pillar stability, 509–512 Bump, 26, 490–491. See also Pressure burst subsidence control, 509 definition, 490 confinement, generation of, 509 description, 490–491 equivalent modulus of layers, 36 flyash, 509 C increase in pillar strength from ashfill, 510 Cable bolt. See Support and reinforcement systems longwall mining Caving pre-driven roadway support, 404, 405 angles, 91–99 subsidence control, 469, 509 bulking factor, 88 pressure burst and gas outburst control, 206 goaf compaction, 88–91 ribside support, 303 initiation and propagation, 85–108 selective placement, 512 subsidence zone models, 86, 427–438 stress-strain characterization, 89 Central Colliery, Australia, 407, 408

# Springer International Publishing Switzerland 2016 671 J.M. Galvin, Ground Engineering - Principles and Practices for Underground Coal Mining, DOI 10.1007/978-3-319-25005-2 672 Index

Chain pillar. See Interpanel pillar; Longwall mining Crinum Mine, Australia, 288, 413 Change management. See Risk management system Cross-cut. See Cut-through Charpy value, 256 Cut-through, 17, 189, 190, 203, 204, 342, 362, 363, Chock. See Support and reinforcement systems 402, 604 Churcha West Colliery, India, 102, 104, 396 Cyclic caving. See Periodic weighting Classical beam theory Cyclic loading. See Periodic weighting applications floor behaviour, 110 D immediate roof behaviour, 84, 229, 274–281, Decline, definition, 15 289–292 Deformation immediate roof strata, 110 behaviour, 34 roadway span, 290–292 brittle, 28 assumptions, 66 creep, 31 axially loaded columns, 69 ductile, 28 definitions, 64 plastic, 28 eccentrically loaded columns, 72 strain hardening, 28 effective length, 69 strain softening, 28 elastic instability, 70 Development roadway end conditions, 65, 286 longwall, 17 Euler–Bernoulli theory, 66 main development, 16 Euler buckling, 70 secondary development, 16 loading Dilation, definition of, 26 statically determinate, 65 Dipping workings statically indeterminate, 65 impacts on radius of curvature, 66 drivage direction, 291 second moment of inertia, 66 ground behaviour, 485 simultaneous axial and transverse loading, 74 ground control, 485 slenderness ratio, 69 mobile equipment operational constraints, 487 support methods, 65 numerical modelling, 486, 487 transversely load beam, 67 risks presented by mobile equipment, 487 Cleat Dolerite sills, behaviour, 102–106 butt, 297 Domains, mining, 3 classification scheme, 298 Drift, definition, 15 definition, 14, 297 Dynamics, 64 design considerations, 303, 482 directional variation, 297 E face, 297 Effective stress law, 40–41 impact on diamond shaped pillars, 174 Elastic modulus longwall mining impacts, 390, 398 elastic, 24 operational considerations, 305–306 equivalent values, 36 (see also Appendix 2) pillar extraction impacts, 482 post-peak, 28 rib stability impacts, 298, 342 pre-peak, 28 CMRR. See Coal Mine Roof Rating secant, 24 Coalbrook Colliery, South Africa, 102, 122, 186, 376, tangent, 24 396, 515, 516 Young’s modulus, 24 Coal Mine Roof Rating, 48–49, 366 Elastic theory Coal, structure and fabric, 14 elastic limit, 24 Cohesion limit of proportionality, 24 definition, 27 load-displacement relationship, 21–23 residual, 44 Poisson’s ratio Consequence. See Risk management system definition, 26 Constitutive behaviour, 36 typical values, 27 Convergence zones and paleochannels, 519–520 proof load, 25 Cook Colliery, Australia, 367 secant modulus, 24 Cooranbong Colliery, Australia, 331 spring constant, 23 Cordeaux Colliery, Australia, 405 stiffness, 21 Coulomb failure criterion, 37 strength, 25 Crandall Canyon Mine, USA, 122, 157, 162–163, 186, stress-strain relationship, 23 301, 312 tangent modulus, 24 Index 673

yield strength, 25 Fall of ground Young’s modulus associated with feather edging, 484 definition, 24 impact on pillar strength, 512–513 typical values, 25 recovery procedures Ellalong Colliery, Australia, 237, 304, 395 augering, 515 Elrington No. 2 Colliery, Australia, 225 on a longwall face, 515 Endeavour Colliery, Australia, 310, 341, 479 shotcrete, bolt and muck remotely, 515 Energy spiling, 513 kinetic, 26 stabilisation and re-mining, 514 potential, 25 traditional approach, 513 strain, 25 working off muck pile, 514 Engineering geology, 3, 4 Feather edging Entry. See Bord, definition contributory factors, 484 Equilibrium controls, 484 stable, 51, 492 description, 483 unstable, 51, 492, 495 Flammable gas, 311 Euler–Bernoulli theory. See Classical beam theory Flatjack, 552 Excavation Flexure zone, 204, 206, 207, 428, 440, 488 abutment stress Flooded workings origins, 91–87, 100, 183 buoyancy effect, 489 profiles for longwall gateroads, 361–362 implications profiles for multiseam workings, 196–202 de-watering strategy, 490 caving and subsidence zone models, 85, 427–438 pillar system load and strength, 490 closure (see convergence) Flooding, 167, 175. See also Inundation convergence, 83 Floor height of softening, 188, 191 failure, 399, 488 impacts on rib behaviour, 298 creep, 460 influence of panel width-to-depth ratio, 87, 91, 328, heave (see also Appendix 4; Bearing capacity) 335–336, 364, 396–397, 404, 423, 441, 445, bearing capacity related, 136, 164–165, 460 502, 517 bord and pillar workings, 136 intersections horizontal stress related, 84, 109, 279 development roadways, 290–292 longwall mining, 193, 366, 370, 371, 391, 406–416 longwall face recovery, 412 multiseam mining, 206 pillar extraction, 310, 317, 318, 346–352 pillar extraction, 349 massive strata impacts, 100–106 pressure burst related, 492, 495 multiseam interaction, 199–206 support and reinforcement, 213 periodic weighting (see Periodic weighting) swelling related, 165 rock mass response, 82 when mining through structures, 507 span influence and design, 87, 106 Footboard, 214 longwall mining, 394, 396–397 Free body diagram, 64 pillar extraction, 334–335 Friction, 28 roadways, 290–292 angle, 27, 37 surface subsidence, 447 coeffficient of, 27 windblast control, 478, 481 internal angle, 37, 38 stress trajectories, 83 Frictional ignition involving rock, 310, 340–341, Experimental panels 508–509. See also Appendix 9 case studies, 515 design considerations, 517 G implementation considerations, 518 Gas explosion, 478 reliability, 515 Gas outburst, 154, 491, 500–503 characteristics, 501 F contributory factors, 501 Failure, 154 description, 500 criterion, 36–40 gas composition, 501 definition, 132–133 legislation and guidelines, 503 mode risk management controls, 501 controlled, 6 Gateroad, definition, 17–18. See also Longwall mining, immediate roof (see Immediate roof) gateroad pillars (see Pillar system) GCMP. See Ground Control Management Plan uncontrolled, 6 Geological feature. See Geological structure 674 Index

Geological model. See Model Highwall mining Geological Strength Index (GSI), 39, 46–48 pillar design, 163 Geological structure pillar strength, 175 cleats and joints, 482 punch, roadway, 15 dolerite sill, 102–106 Hoek–Brown strength criterion dyke, 504 coal mass strength, 35, 142, 146 fault, types, 503 concept, 38–40 impacts on Homestead Colliery, Australia, 405 bumps and pressure bursts, 493–495, 504 Huntley Colliery, New Zealand, 301 inrush and inundation, 426 Hydraulic fracturing inrush potential, 488 for in situ stress measurement, 556 longwall mining, 398 windblast control measure, 479–483 mining at shallow depth, 111, 115 Hydrofracturing. See Hydraulic fracturing mining conditions, 504 pillar extraction, 341, 343–344 I pillar strength, 170, 174, 175 Immediate roof pillar system failure, 506 failure modes regional mine stability, 504 abutment shear, 273, 277 water inflow to mine, 438 buckling, 273 water crack, 343 compression, 273, 280 Geomechanics, 4 discontinuity controlled, 273–276 Geophysical Strata Rating, 49 flexure, 273, 278–279 Geotechnical engineering, 3 Inbye, definition, 16 Geotechnical model. See Model Incline, definition, 15 Goaf. See also Pillar extraction Inrush and inundation compaction, 88 barrier pillar design, 488 definition, 18 case studies, 487 encroachment into the workplace, 344 critical causation factors, 487 falls, 341 definition, 487 goaf edge behaviour, 346 flexure zone impacts, 440, 488 goaf edge control, 343 impacts of geological structure, 426, 438–439 on two or more sides, 345 legislation and guidelines, 427, 487 Gob. See Goaf in pillar extraction, 352 Gordonstone Colliery, Australia, 94–96 piping related, 439 Griffith crack theory, 39 rescue precautions re decompression sickness, 488 Ground Control Management Plan (GCMP), 204, 544. risk factors, 439 See also Appendix 18; Risk management system subsidence induced, 426 basis, 527–528 Interaction between workings competencies of personnel, 528–532 in adjacent seams, 182, 196–207, 342 risk management advice, 562–563 in the same seam, 182–196 structure, 528 Interpanel pillar Ground engineering, 2 applications and design history, 5 (see also Appendix 1) bord and pillar mining, 128 Ground model. See Model hydraulic mining, 326 Ground response curve longwall mining, 18, 328, 360–186, 374, 390 concept, 52–53 (see also Longwall mining, chain pillar) ground support systems, 212 multiseam mining, 196–205, 404 longwall face, 385–386 pillar extraction, 328, 335, 338, 340 pillar extraction, 335–336 pressure burst control, 338 pillar system, 170–171 case studies GSI. See Geological Strength Index Coalbrook Colliery, 186, 515 GSR. See Geophysical Strata Rating Crandall Canyon Mine, 186 Guttering, 87, 109, 110, 295, 302, 379, 387, 393, 397, description, 17 407, 409 functions applications and design, 197 H managing uncertainty, 518 Headboard, 214 multiseam mining, 196–205 Heading, definition, 17 pressure burst control, 498 Height of softening, 188, 191 within a seam, 124, 155, 161, 182–196, 506 Index 675

influence in multiseam mining, 440 negotiating weak roof and cavities, 389 influence on powered support advance, 389 caving, 99, 338, 437 powered support setting pressure, 389, 390 surface subsidence, 93, 423 rate of retreat, 388 interpreting overlying surface subsidence, 93 real time pressure monitoring, 390 load face operational variables critical and supercritical panel width, 93 cutting technique and support configuration, influence of massive strata, 103 386–387 influence of superincumbent strata stiffness, 99 face operating practices, 388–390 panel corners, 100 powered support system maintenance, subcritical panel width, 98 387–388 ISO 31000. See Risk management system face recovery, 412–414 face strata control (see also face operating factors) K coal face behaviour, 390–391 Kinematics, 64 convergence impacts and control, 378–379 Koornfontein Colliery, South Africa, 512 ground response curve, 385–386 immediate and upper roof strata, 392 L other influencing factors, 390 Lemniscate linkage, 313, 374, 377, 384, 388, 557 periodic weighting management, 394–398 Likelihood. See Risk management system roof cavity causes and control, 392–394 Linear arch tip-to-face distance, 393, 394 applications, 104, 105, 108, 272, 395 floor strata control theory, 75–76 failure, 399 Linear regression, 60, 287 heave, 370, 371, 391, 406 Load gateroad Euler, 70 abutment stress, 361–362 pillar (see Pillar system) behaviour, 367–374 proof, 25 horizontal stress impacts & mitigation, 189, tributary area, 91, 94, 95, 130–131, 144, 151, 159, 362–363, 367–370 163, 175, 334, 336, 337, 364, 484, 489, 494, 506 layouts for multiseam, 202 Loading system layouts for single seam, 362–363 displacement controlled, 21, 381, 493 orientation, 362–363, 398 load controlled, 21, 381, 493 serviceability, 186 Logistic regression, 61 stress notch, double, 192, 294 Longwall mining stress notch, single, 189, 288, 367–370 chain pillar (see also Interpanel pillar) vertical stress mitigation, 360–362 abutment loading, 363–364 installation roadway behaviour, 367–374 drivage direction and sequence, 399–401 crush pillar (see as a yield pillar) ground stability controls, 401 design, 186, 364–367 horizontal stress mitigation, 189, 401–403 design, numerical modelling, 366–367 risk of tensile failure, 403 life cycle, 363–364 sacrificial roadway, 401–403 multiseam layouts, 202 (see also Interpanel pillar) maingate (see gateroad) numerical modelling, 365 numerical modelling potential for stress relief, 193 chain pillar design, 193, 365–367 primary function, 364–365 multiseam layouts, 199 yield pillar, 366–367, 370 roof failure and fracturing, 392–393, 395–396 cutting technique periodic weighting, 394–398, 412 bi-directional (bi-di), 386 controls, 397–398 half web, 387 powered supports uni-directional (uni-di), 387 basic functions, 378–379 cyclic caving (see periodic weighting) bearing capacity of roof and floor, 384 cyclic loading (see periodic weighting) canopy balance, 383 face break, 381, 390, 404, 406, 411 canopy ratio, 383, 393 face operating factors contact advance, 389, 394 debris, 389 contact pressure, 381 extended downtime procedures, 390 historical development, 374–378 face alignment, 388 leg pressure in real time, 557 horizon control, 388 lemniscate linkage, 374, 377, 379, 384, 388, 557 676 Index

Longwall mining (cont.) Mining method loading models, 380–383 bord and pillar (see Bord and pillar) manufacturer specifications, 381 bord and pillar second workings (see Pillar extraction) performance characteristics, 374–378 bottom coaling, 336 performance factors, 379 cut and bolt, 17 roof contact conditions, 386 cut and flit, 17 setting load, 384 first workings, 17 setting pressure, 393 highwall, 18 static and kinematic characteristics, 379–386 longwall (see Longwall mining) stiffness, 384 panel and pillar (see Pillar extraction) support density (see support resistance) pillar and stall (see Bord and pillar) support resistance, 380–381, 384 pillar extraction (see Pillar extraction) tip load capacity, 374, 394 pillar recovery (see Pillar extraction) tip-to-face distance, 388, 406, 412, 507 pillar robbing (see Pillar extraction) yield load, 384 retreat mining (see Pillar extraction) yield pressure, 393 room and pillar (see Bord and pillar) pre-driven recovery roadway second workings, 17 behaviour during holing, 406–412 secondary extraction, 17 case studies, 406–412 stooping (see Pillar extraction) potential adverse impacts, 406 (see also pre-driven top coaling, 336 roadway in longwall block) Mining through a fault or dyke risks, 403–406 drivage sequence, 506 types, 405 fault types, 503 pre-driven roadway in longwall block ground control options, 505 case studies, 404 ground preconditioning, 507 longwall recovery roadway, 405–412 longwall mining considerations, 507 risk profile, 403–404 risk factors, 503–508 stabilisation preparatory measures, 404 Model types, 403 geological, 3–4, 538 spontaneous combustion considerations, 360–361 geotechnical, 3–4, 379, 538 stress notch (see gateroad) ground, 3–4, 538 system stiffness, 379 Mohr failure criterion, 37 tailgate (see also gateroad) Mohr–Coulomb failure criterion, 38, 46, 493 abutment stress, 187 Monitoring and instrumentation behaviour, 371–373 basis of instrumentation, 546–547 stress relief, 193–196 borehole stress relief devices support and reinforcement, 202–222, 361 ANZI cell, 554 types of longwall method CSIR doorstopper, 554 description, 17 CSIRO Hollow Inclusion cell, 554 integrated longwall mining with sublevel caving, 414 CSIR triaxial strain cell, 554 longwall mining on the advance, 360–361 coal roof subtleties, 295 longwall mining on the retreat, 360–361 displacement monitoring instrumentation LTCC (longwall top coal caving), 414 borescope, 547 miniwall, 415 convergence pole, 547 non-integrated longwall mining with extensometer, 547–552 caving, 414 field monitoring practices, 560–561 soutirage, 414 flatjack, 552 web, 18 groundwater pressure monitoring, 560 high roof, practicalities in reaching, 296 M load and pressure monitoring, 557 Measurement monitoring parameters, 22 purpose, 543–544 Syste`me Internationale,20 strategy, 544–545 units, 22 sensory monitoring, 545–546 Metropolitan Colliery, Australia, 373 sounding the roof, 546 Middlebult Colliery, South Africa, 313 shear movement detection, 559–560 Mine plans stress monitoring and measurement reliability, 487 borehole profile techniques, 556 sources of unreliability, 488 borehole stress relief techniques, 553–556 Index 677

free surface techniques, 552–553 O hydrofracturing, 556 Operating discipline, 174, 312, 356 tilt and slope monitoring, 560 Operational hazards, 477–523 Monte Carlo analysis, 63 Outburst. See Gas outburst Moonee Colliery, Australia, 479–481, 483 Outbye, definition, 16 Moranbah North Mine, Australia, 508 Moura No. 2 Colliery, Australia, 310, 311 P Moura No. 4 Colliery, Australia, 310, 479 Pacific Colliery, Australia, 407, 408 Multiple linear regression, 60 Parametric analysis, 57 Multiseam workings, 182, 196–206 Periodic weighting design, 206 description, 87 extraction order, 182, 206 longwall mining flexure zone, 204 controls, 397–398 interaction factors, 196 at face recovery location, 412 interpanel pillar precursors, 397 pillar systems, 197 pillar extraction, 339–340, 352 total extraction, 199 Phalen Colliery, Canada, 396 longwall Phenolic foam, 265–266 superpositioning, 202 Pillar, definition, 17 mining methods, 182 Pillar extraction numerical modelling, 199, 207 ABLS (see MRS) pillar extraction, 342 Alpine breaker line support (see MRS) vertical stress distribution, 196 bottom coaling, 485 Munmorah Colliery, Australia, 508 breaker lines Myuna Colliery, Australia, 331 MRS (see Pillar extraction, MRS) rock bolt, 320, 353–354, 484 N timber, 216, 313, 320, 353, 484 New Denmark Colliery, South Africa, 328, 330, 404 continuous miner Newstan Colliery, Australia, 396, 406, 407, 478, 479, 482 on-board operator, 310, 312, 319, 346 Newton’s Laws, 19 remote control, 312, 319–326, 351 Numerical modelling design guidelines chain pillar design, 193, 365 ARMPS, 312, 337–338 dipping workings, 487 MDG-1005, 312 effect of panel width-to-depth ratio, 112 design parameters and considerations effect of structure on pillar strength, 163 abutment stress, 339–340, 349 far-field displacements, 448 cleats and joints, 342 fender behaviour in pillar extraction, 346 examples in practice, 342–343 ground support, 288–289 existing ground support, 344 hydrogeology, 430, 440 existing workings, 344 longwall panel design, 397 fenders, 346 longwall roof fracturing, 392–393 flammable gas, 340, 341 methodologies, benefits and limitations, 6, 55–58, frictional ignition, 310, 340–341 112, 126, 147–150, 162 gas explosion, 310, 311 multiseam mine design, 199, 207 geological structure, 343–344 output assessment goaf edge control, 353–355 parametric analysis, 57 ground response curve, 335–336 sensitivity analysis, 57 inrush, 340, 352 pillar extraction manner and sequence, 345–346 interpanel pillars, 326, 335, 338, 340 pillar extraction panel design, 335–336 intersections, 317, 318, 345–352 pillar load in irregular layout, 174 load distribution, 334–336 pillar system applications, 147–150, 162 manner and sequence of extraction, 344–346 pillar system design, 168 mining height, 336 shear stress distribution in tendon, 246 numerical modelling, 335–336, 345–346 specifications operating practices, 355 boundary conditions, 57 panel width, 334–335, 351 constitutive laws, 57 periodic weighting, 339–340, 352 failure criteria, 57 safety factor, 336, 352 material properties, 57 spontaneous combustion, 310, 311, 334, 340–341 yield pillar behaviour, 366–367 stooks, 346–352 678 Index

Pillar extraction (cont.) risk profile, 310–313 ventilation, 318, 327, 333, 334, 340–343 safety performance windblast, 311, 330, 333, 334, 339–341, 352, 356 advances, 312–313 extraction line orientation, 316 Australia, 311–312, 346 finger line, 313 USA, 312, 347, 350 goaf stability behaviour, 311 at the extraction line, 344–355 edge control, 313, 317, 319, 328 floor bearing capacity, 168 encroachment into workplace, 352–356, 484 monitoring, 352–353 falls of ground, 312, 327 panel basis, 343–352 operator exposure, 310, 312, 317, 336 regionally, 333–343 two or more sides, 322 vicinity of geological structures, 344 green, 316–318 standing, 316, 317, 344 horizontal stress mitigation, 326 stook (see also design parameters and considerations) incidents (see also Appendix 9) description, 315 Endeavour Colliery, 310, 312 terminology Moura No. 2 Colliery, 310 pushout (see also stook) Moura No. 4 Colliery, 310, 312 snook, 315 methods-general description, 310 stump, 315 methods-partial extraction windblast (see design parameters and considerations) definition, 17 Pillar system panel and pillar, 17, 161, 331, 460 components, 122 pillar stripping, 174 effective pillar width, 137–140 methods-total extraction failure incidents, 122–123, 157–158 advancing, 326 holing longwall recovery roadway, 405–412 Christmas tree, 319 related to geological structure, 170, 505 continuous haulage systems, 322–326 failure modes, 6, 150, 154–158, 162 diagonal splitting, 317–318 controlled, 154 double sided panel, 317 creep, 155 fishbone, 319 massive, 156 hydraulic mining, 326–328 squeeze, 155 lifting left and right, 319–326 uncontrolled, 155 Modified Old Ben, 318 yield, 366–367 Munmorah, 318 footing, 135 Old Ben, 318 foundations, 164–169 open ended lifting, 317 bearing capacity, 135–136 rib pillar, 319 creep, 460 shortwall, 326 definition, 135 single sided panel, 317 functions, 123–125 skirting, 317 ground response curve, 170–171 split and lift, 318 influence of treetopping, 319 interfaces, 133–134, 487, 494, 495 twinning, 319 pillar width-to-height ratio, 132–137, 156, Wongawilli, 318–319, 346 158–164, 168, 170, 175, 366–367, MRS 495, 518 advantages, disadvantages (see Appendix 10 ) stiff overburden, 164 as breaker line support, 354–355 time, 153 description, 313 influence of geological structure hazard reduction role, 312 chromate pillar failures, 505 in longwall face recovery, 414 coal pillar failures, 170 operational aspects (see Appendix 10 ) faults, 505 under massive strong roof, 346 joints, 170 when lifting left and right, 320–322 load, 126–128, 174, 183 operating discipline, 312, 356 irregular pillar layout, 130 pillars regular pillar layout, 127 green, 316–318 shallow depth, 115 standing, 316, 317, 344 tributary area load, 127–128, 130–131 pushout, 315 old workings, 153 risk management probabilistic based design, 150–154 standards and guidelines, 312 safety factor, 150–154, 162–164, 168, 170–171 Index 679

strength Probabilistic based analysis, 59–64 confined core concept, 137, 146, 154, 156–158, uncertainty 183, 301, 370 aleatory, 152 defining strength and failure, 132–133 epistemic, 152 determinations in situ, 142–143, 150, 162 PUR. See Polyurethane resin (PUR highwall mining pillars, 163, 175 impact of roof falls, 512–513 Q linear strength formula, 141, 150, 172 Q system. See Tunnelling Quality Index power strength formula, 150, 172 seam specific, 170 R squat pillar strength formula, 145, 172 Radius of curvature, definition, 66 stress, 125–131, 183 Rib (sidewall) stability associated with UNSW methodology bottom coaling, 485 features and limitations, 172–173 diamond shaped pillars, 150, 174, 322, 363, 517, 518 probabilities of stability, 151 dipping workings, 487 Pillar type longwall face, 391 abutment, 17 Rib (sidewall) stability impacts of forming barrier, 17 (see also Interpanel pillar) an excavation, 298 chain, 18 (see also Interpanel pillar) Risk. See Risk management system crush (see yield) Risk assessment. See also Risk management system diamond shape, 174, 342, 517 bases for determining acceptable risk green, 317, 318 annualised fatalities, 541 highwall, 18 design life, 542 panel, 17 low as reasonably practicable (ALARP), 527 parallelepiped shape, 126 qualitative perceptions, 542 protective, 454, 468 so far as is reasonably practicable (SFARP), 527 remnant bow tie analysis, 8, 535 multiseam situations, 200, 342, 494, 498 context, 535–536 pillar extraction, 123, 311, 315, 352, 478 controls stabilising, 161, 338, 498 heirarchy, 537 web, 18 process quality considerations, 535–538 yield, 164, 366–367, 482, 497 residual risk, 537 Pit bottom, definition, 15 reviewing a risk assessment, 542–543 (see also Risk Poisson’s ratio, 26 management system) Polyurethane resin, 264–265, 472, 508 team composition, 536 Pore pressure, 40 types Pressure arch, 84 Event Tree (ETA), 534, 535 Pressure bump. See Bump; Pressure burst Failure Modes and Effects Analysis (FMEA), 533 Pressure burst Fault Tree (FTA), 533, 534 Crandall Canyon, 122–123 Workplace Risk Assessment and Control description, 490–491 (WRAC), 533, 534 fatalities Risk management system Australia, 297, 500 definition of terms USA, 312 consequence, 7 mechanics hazard, 7, 526 capacity to store energy, 491 likelihood, 7, 59, 526 confined core concept, 156–158, 302, 367 as low as reasonably practicable, 527 discontinuity related, 496 probability, 59, 526 fault plane related, 504 risk, 7 influence of confinement, 494, 495 risk management, 526 influence of interfaces, 494, 495 threat, 7, 526 influence of pillar width-to-height ratio, 495 Trigger Action Response Plan, 538 Mohr–Coulomb, 493 framework, 8 multiseam mining related, 342 implementation of plan pre-requisite conditions, 492 change management, 540–541 rock mass failure, 494–495 considerations, 541 role of geological structure, 494 determining acceptable risk, 541–542 risk management hazard plans, 538 controls, 497 reviewing a risk assessment, 542–543 mitigation, 206, 304, 496 reviewing plan effectiveness, 539–540 680 Index

Risk management system (cont.) irregular shaped coal pillars, 174 Trigger Action Response Plan (TARP), 118, 386, longwall mining, 150 538–539 multiseam workings, 198 monitoring pillar extraction, 150, 336, 352 purpose, 543–544 pillar system foundation failure, 164, 168 strategy, 544–545 tendon design, 229 risk analysis and assessment (see also Risk coal pillars assessment) effect of geological structure, 170 bow tie, 8, 535 risk management considerations, 168 foundations, 532–533 safety factor-probability correlation, 151, 171 standards and guidelines concept, 58–59, 170 AS/NZS-3905.19, 541 limitations, 58, 62 AS/NZS-9001, 541 Safety performance ISO 31000, 7–8, 312, 528 overall in Australia, 8 MDG-1005, 312 pillar extraction MDG-1010, 9, 312, 533 Australia, 310–312, 346 MDG-1014, 9, 542 USA, 310–312, 347, 350 uncertainty pillar system failures, 122–123 aleatory, 152 pressure burst fatalities epistemic, 152 Australia, 297 workplace risk control requirements, 527 USA, 312 Risk profile rib fall injuries and fatalities pillar extraction, 310–313 Australia, 297 pillar systems, 122–123 Sasol Colliery, South Africa, 408 ribs, 296 Seismicity RMR. See Rock Mass Rating System microseismic monitoring applications Robens inquiry, 7 bumps and pressure bursts, 490, 497, 499 Rock bolt. See also Support and reinforcement systems displacement on geological structures, 98, alternative applications, 519 496, 507 safety precautions, 518–519 identifying subsurface subsidence zones, 435 Rockburst, 490. See also Pressure burst longwall mining induced fracturing, 94, 200, 392, Rock mass 396, 398, 433 blocky, 6 pillar testing in situ, 137, 495 classification systems, 46–50, 287–288 windblast risk management, 480, 483, 499 deformation, 14 microseismic survey fabric, 19 to detect and characterise geological structure, fractured, 19 506, 507 intact, 19 seismic events jointed, 6 bumps and pressure bursts, 491 terminology, 21 on fault planes, 496 Rock Mass Rating System, 46 pillar system failures, 122 Rock mechanics, 6 seismic monitoring Rock Quality Designation (RQD), 46 principle of operation, 26, 557–559 Roof Strength Index (RSI), 49 purpose, 6 Room, 17 Shaft, definition, 15 RQD. See Rock Quality Designation Shallow mining, 111–118 RSI. See Roof Strength Index effect of geological structure, 115, 175 S panel width-to-depth ratio, 112 Sacrificial roadway, 189, 294, 401–403. See also Stress water ingress, 114 Safety factor highwall mining, 175 applications longwall face recovery, 412 bord and pillar workings, 150 longwall hazards, 116 coal pillar design, 123 risk management coal pillars generally, 150–154 controls, 116 coal seam specific strength, 170 plan, 118 diamond shaped coal pillars, 174 Shear angle. See Caving Euler buckling, 72 Sigma Colliery, South Africa, 376 highwall mining pillars, 19 Sounding the roof, 546 irregular pillar layouts, 131 South Bulga Colliery, Australia, 396 Index 681

Spiling Stress applications abutment (see also vertical) recovering buried equipment, 354 associated with pillar failure, 186 roof fall recovery, 513 chain pillar life cycle, 363–364 verandah ahead of face, 389, 507 effect on foundation stability, 370 Spontaneous combustion, 310, 334, 340–341, 360–361. impacts on chain pillars, 370 See also Appendix 9 impacts on holing a pre-driven roadway, 405 Spring constant, 23 impacts on longwall face floor, 391–392, 398 Springvale Colliery, Australia, 430, 432 implications for pressure bursts, 494 SSR. See Stress Strength Ratio influence of panel span, 339–340, 391, 396, 448, Stall, 17 481 Statics longwall mining, 187, 192, 370 basic principles, 64–77 mapping on hazard plans, 538 longwall powered supports, 379–386 multiseam total extraction layouts, 196 Statistical analysis, 59–64 origins, 87, 91, 106, 183, 350 Stiffness, 21 pillar extraction, 317, 318, 322–326, 334, 336, bending (see flexural rigidity) 339–340, 343, 351 cable bolt, 251 prediction, 107 conceptualisation of system stiffness, 423 profiles for longwall gateroads, 361–362 definition, 24–25 reduced stress situations, 265 encapsulating medium, 242 coal, 43 longwall mining system, 379 deviator, 29 longwall powered support, 384 effective normal, 40 MRS, 313 Euler, 71 overburden, 112, 164, 170–171, 333, 346 field, 42 pillar extraction, 348–349 horizontal pillar system, 125–127, 170–171 about roadways, 187 post-peak, 28 impacts on longwall installation roadway, regional mine, 91 362–363, 399 testing machine, 51 impacts on longwall roadway orientation, 362–364 Stonedust, 155, 343, 546 impacts on stiff roof beds, 401 Stowage, 469. See also Backfill impacts on surface subsidence, 447, 448 Strain major, 42 axial, 26 minor, 42 burst, 490 (see also Pressure burst) mitigation measures, 109, 110, 187, 294, 326, deviator, 32 367–370, 399, 401–403 failure criterion, 39 reduction at shallow depth, 112 hardening, 28 relief in pillar extraction, 326 lateral, 26 shadow, 187, 326, 399, 402 principal, 29 sources of elevated stress, 42, 82, 370 shear, 29 intermediate, 29 softening, 28 lateral (see horizontal) Strata Control Principal Hazard Management Plan. See lithostatic, 42 Ground Control Management Plan (GCMP) major principal, 29 Strata Failure Management Plan. See Ground Control mining-induced, 42 Management Plan (GCMP) minor principal, 29 Strength normal, 27 definition, 25 notch, double, 192, 294 flexural notch, single, 189, 288, 367–370 definition, 67, 230 path, 34 values, 230, 282 pre-mining, 42 laboratory testing, 34, 141, 160–161 primitive, 41–43 post-peak, 28 principal, 29 rock, 31–36 radial, 29 shear, 36–38, 44–45, 133 resultant, 42 in situ testing, 35, 142 shear, 27 triaxial, 32 sign and direction conventions, 29 uniaxial compressive, 32 strength ratio, 49 yield, 25 tectonic, 42 682 Index

Stress (cont.) horizontal displacement, 444 vertical, 183 (see also abutment) horizontal distortion, 445 virgin (see primitive) influence of panel width-to-depth ratio, 91 Stress corrosion cracking, 255–256 shear strain, 445 Stress Strength Ratio, 49 tensile strain, 445 Subsidence, generic tilt, 445, 446 brief history, 422 uplift, 451 classification of significance valley bulging, 449 effects, impacts and consequences, 422 vertical displacement, 444 conceptualisation horizontal stress system stiffness, 423 impacts on surface subsidence, 448 vertical surface displacement, 423 impacts (see also Appendix 12) definition, 422 built environment, 464–465 generic mine layouts determinants, 464 critical panel width, 423 far-field displacements, 468 subcritical panel width at considerable depth, 423 mitigation and remediation, 468–472 subcritical panel width at shallow depth, 423 sinkholes and plug failures, 464 supercritical panel width, 423 surface watercourses, 465–467 Subsidence, subsurface. See also Subsidence, generic valley closure, 467–468 angle of draw, 87 structural damage classification schemes, 464 caving and subsidence zone models, 86, 427 numerical modelling limitations of models, 437 far-field displacements, 448 discontinuous subsidence, 92, 103, 334 plug failure, 441 effects, 427–438 pothole (see sinkhole) mitigation, 441 prediction of effects environmental angle of draw, 454–455 considerations, 423, 427 far-field movements, 462–464 impacts, 439, 440 magnitude, rate, duration, 460–462 flexure zone, 204 in multiseam mining, 460 impacts, 440 tilt, strain, curvature, 456–460 fluid flow fundamentals upsidence, 462 bulk porosity, 425 valley closure, 462 cubic law, 426 vertical displacement, 455–456 Darcy’s law, 425 prediction techniques drainage, 424 analytical, 453 hydraulic conductivity, 425, 426 graphical, 453 impact of geological structure, 438 hybrid, 454 permeability, 425 incremental profile method, 453, 456 subsidence fracturing, 424 influence function, 454 hydrogeological models (see caving and subsidence numerical, 453 zone models) profile function, 453 impacts, 427 reliability, 454–460 environmental, 439 upper bound, 453 gas release, 441 protective pillar, 454 risk of inrush and inundation, 426, 439 (see also risk management controls Appendix 11; Inrush and inundation) adaptive management, 468 numerical modelling interpanel pillars, 373–374 hydrogeology, 430, 440 panel width-to-depth ratio, 91 Subsidence, surface protective pillar, 454 angle of draw, 87, 443 sinkhole, 114 reliability of predictions, 454–455 description, 441, 442 chimney cave, 114, 441 likelihood factors, 441 classical subsidence model site-centric subsidence, 447–452 assumptions, 442 structural damage classification schemes, 464 behaviour, 442–447 (see also Appendix 12) effects types of behaviour compressive strain, 445 chimney caving (see sinkhole) curvature, 444 classical subsidence, 422 far-field displacement, 449 conventional, 422 Index 683

disordered (see site-centric subsidence behaviour) applications, 412, 413, 513 non-systematic (see site-centric subsidence cementitious, 221–222 behaviour) timber, 220–221 ordered, 422 cross support, 259–261 plug failure, 441 applications, 258, 281–307, 513 sinkhole, 441 definitions site-centric, 422 active support, 212 systematic, 422 ground support, 212 trough, 441 passive support, 212 unconventional (see site-centric subsidence primary support, 212 behaviour) reinforcement, 212 upsidence, 449–453, 462–464 secondary support, 212 valley closure, 449–453, 462–464 support, 211 Support and reinforcement design. See also Support and temporary support, 216 reinforcement systems tertiary support, 212 considerations ground response curve, 212–213 angled tendons, 235–236, 281–307, liner, 263 411, 505 membrane, 263, 411 applicability of pretension, 229, 239, 251, 294 mobile breaker line support (see Pillar extraction) coal roof subtleties, 295 mobile roof support (see Pillar extraction) long centre tendons, 284–287, 292–294 pillars, 223 (see also Pillar system) mining through cross measure strata, 296 powered support (see Longwall mining) reinforcement density indices, 288–289 prop reliability of UCS–E correlations, 287 friction, 216 rock mass classification systems, 287 hydraulic, 216 scope for numerical modelling, 289 specialised, 216 stress relief effects on anchorage, 294–295 timber, 215–216 (see also timber prop) timing of installation, 292–294 rock bolt (see tendon) floor integrity, 295 (see also Floor) screen, 261, 412–413 immediate roof spiling (see also Spiling) bending-v-buckling, 278 applications, 354, 389, 507, 513 classical beam theory, 282–284 standing support failure models, 282–307 definition, 213 failure modes, 272–273 floor heave control, 370 generic design methodologies, 273–282 longwall installation roadway, 400 intersections, 278, 291–292 longwall recovery face, 407 ribs (sidewalls) pillar extraction, 310, 349 behaviour modes, 298–303 pre-driven roadway in longwall block, 404, causes of deterioration, 296 409–410 composition, 297–298 tailgate support, 361, 372 definitions, 296 strata binder design considerations, 303–304 applications, 472, 508 (see also Polyurethane effects of an excavation, 298 resin) hardware considerations, 304–305 surface restraint, 258–263 impact of mining height, 303 system properties operational considerations, 305–306 load capacity comparisons, 223 risk profile, 297 primary characteristics, 212 support systems, 297, 302 tendon Support and reinforcement systems anchorage technique, 225–226 arches and sets, 222 angled, 235–236 (see also Support and cable bolt (see also tendon) reinforcement design) angled, 235–236, 281–307, 411, 505 definition, 223 applications, 191, 258, 354, 404, 410–413, 505, end anchored, 226, 251–252 513, 514 face plate, 253–254 centred, 281–307 friction anchored, 252–253 classification, 224 fully encapsulated, 227 composition, 223 function, 225 post-grouting, 257 gloving, 254–255 chock history, 224 684 Index

Support and reinforcement systems (cont.) Top and bottom coaling, 484–485 impact of stress relief, 294–295 Tower Colliery, Australia, 451 installation technique, 257–258 Tributary area theory, 127. See also Load load transfer, 226, 251–252 Trigger Action Response Plan, 118, 386, 538–539. See performance variables, 226, 294 also Risk management system point anchored (see end anchored) Tshikondeni Colliery, South Africa, 514 post-grouting, 257 Tunnelling Quality Index, 46 pretension, 229, 239–251, 257 (see also Support and reinforcement design) U resin, 257 Upsidence, 449–453, 462–464 resin anchor, 239 safety precautions, 257–258 V shear stress distribution, 250–251 Valley closure, 449–453, 462–464 stress corrosion cracking, 255–257 Ventilation, 291, 318, 327, 333, 334, 340–341, 361, 399, surface profile, 241 478, 503 suspension mode, 227–229 Vierfontein Colliery, South Africa, 353 types, 223 Voussoir beam, 75. See also Linear arch thin liner (see membrane) thrust bolting, 229, 235 W timber prop Water crack. See Geological structure breaker line, 216, 313, 317, 353, 354, 484 Windblast capacity, 214, 215 (see also Appendix 6) case studies, 479, 482 legs for cross support, 258, 259, characterization 404, 508 overpressure and velocity, 480 setting procedure, 215 (see also Appendix 7) definition, 478 void filler, 265–266 description, 478 Syste`me Internationale,20 hydrofracturing, 479 legislation and guidelines, 483 T pillar extraction, 311, 352 Tahmoor Colliery, Australia, 327, 465 risk management, 481 TARP. See Trigger Action Response Plan controls, 481 Threat. See Risk management system management plan, 481 Thrust bolting, 229, 235 source, 478