000_COVERS.qxd 2/13/1950 7:25 PM Page 3 000_COVERS.qxd 2/13/1950 7:25 PM Page 4 I take this opportunity to congratulate the USBRL team for appreciable work done on the project in the last one year and for bringing out the publication of the 12th issue of this Technical Magazine Himprabhat.

The -Srinagar- Rail Link (USBRL) is a treasure trove of knowledge, new techniques, state-of-the-art technology and varied experience for engineers and is, thus, a unique project in the annals of Indian Railway. The magazine not only provides the details of experience gained during the course of implementation of the project but also provides a platform for the project team to share their views. This is a very commendable effort for documenting the important facets of challenges in the for contemporary professionals as well as for posterity.

I hope that USBRL maintains the momentum and spirit and continues to move forward in realisation of dreams of connecting to the Indian Railway network as well as to take forward this fascinating journey of publication of a magazine to enrich all experienced and young engineers alike. I am glad to see the 12th issue of Himprabhat Technical News Magazine giving an account of the achievement of technical marvels and the challenges faced by the USBRL Organisation of Northern Railway. The USBRL team has had a breakthrough in tunneling efforts, excavating 26.34 km in 2018-19 against last year’s progress of 17.05 km, which is 54.5% more compared to last year. Actual expenditure too surged to `2,587 crore i.e crossing `2,500 crore impelling paradigm shift on progress of work.

The unprecedented work is being chronicled by publication of Himprabhat. I find that the magazine covers a wide variety of topics and activities enumerating the details of work carried out, the challenges faced and the measures adopted the USBRL team’s initiative and endeavour. The efforts in publication of this magazine are laudable and deserve to be complimented.

I am sure the USBRL team will maintain the momentum and spirit this year to surpass the benchmark set up last year and also to continue to chronicle the knowledge and experience by periodical publication of this magazine. The USBRL Rail Link Project was envisioned with a view to provide reliable and efficient mass transportation system and to connect the Kashmir Valley with the rest of Indian Railway network. The 12th issue of Himprabhat lives up to the technical standards that had been laid in the previous issues of the magazine.

This issue of Himprabhat captures a rich and varied technical experience of project engineers and international consultants encompassing a wide gamut of activities on tunnels and in the mountainous terrain of Himalayas. I have vivid memories from my last visit on how engineers overcame technical challenges deep inside tunnels or while building piers on steep cliffs facing over deep gorges. It is an endeavour of this magazine to document every innovative work on USBRL for posterity to cherish and learn lessons. It is a matter of pride and huge satisfaction that works on tunnels and bridges are progressing very well.

I wish that USBRL takes forth this fascinating journey in the magazine to enrich the knowledge of all engineers. FROM THE EDITOR IN CHIEF’S DESK t gives me immense pleasure to apprise tackle difficult ground situations typically that concerted and sustained efforts by encountered in fault sections and ensure team USBRL made it possible to achieve adequacy of support selection during all time high tunnel excavation of 26.34 excavation of tunnels. Km in 2018-19 against last year progress The alignment USBRL Project passes Iof 17.05 Km. Also, expenditure incurred for through the difficult geology in Himalayas. the year 2018-19 is `2587/- crores ie crossing Thorough knowledge of geology is imperative `2500/- Crores mark against the last year for successful execution of engineering projects expenditure of `2088.5/- Crores. The above in Himalayas.The article by Sh. Aejaz Ahmad, two parameters are ever highest since the start Geotechnical expert, PEMS engineering of USBRL project. I take this opportunity to consultant and Pratap Chandra Dhang, VIJAY SHARMA assure that USBRL project will continue to Dy.GM/C/Geology/IRCON International Editor-In-Chief strive and make sincere endeavours to further Ltd.covers descriptive methodologies for the take up challenges and surpass the bench mark geological and geotechnical works during set up in preceding year. construction of railway tunnels in Himalayan As we all know, the project is passing AS WE ALL KNOW, region. This article provides the geological through the most difficult geology, Surprises THE PROJECT IS assessment of the ground during construction PASSING and imponderables are a routine affairs. So, THROUGH THE stage of tunnel. The narrative provided in the does the ingenuity and the undying spirit of MOST DIFFICULT paper gives simple and compact methods of engineers, geologists and other experts in the GEOLOGY, tunnelling process through this young SURPRISES AND field. For every difficulty and challenge, they IMPONDERABLES Himalayan Mountain Belt. work out solutions and move ahead with their ARE A ROUTINE The article by Sh. Sandeep Gupta Chief AFFAIRS. SO, DOES experiences and knowledge. Their work and THE INGENUITY Engineer/South/USBRL Project,Sh. Sumeet experiences are once again chronicled and AND THE Khajuria Deputy Chief Engineer/ recorded in this issue of Himprabhat. This UNDYING SPIRIT & Sh.Anirudh Bansal Executive OF ENGINEERS, publication includes very useful articles and GEOLOGISTS AND Engineer/Katraon "Rectification of Up-heaved case studies which will definitely inspire OTHER EXPERTS portion of Ballast less Track(RHEDA 2000- IN THE FIELD. FOR engineers and professionals alike and enrich EVERY DIFFICULTY VOSSLOH 300-1Usystem) laid in Tunnel them with fruitful knowledge and AND CHALLENGE, T-25 on Udhampur-Katra section under information. THEY WORK OUT running traffic conditions, by employing an SOLUTIONS AND Riella.A., Quaglio.G., Sikka. V. and MOVE AHEAD innovative non-destructive method using Zammit. H. of Geodata SpA, Italy and WITH THEIR specially designed VOSSLOH 300-1U EXPERIENCES AND in their article Tackling squeezing Ground KNOWLEDGE. fittings" has added a new dimension towards during Tunnel T1 Excavation have shared their THEIR WORK AND the maintenance & repair work of Ballast less experiences involving various phases like EXPERIENCES ARE track, which can be done under running traffic ONCE AGAIN geological studies of the tunnel strata, analysis CHRONICLED conditions for such peculiar problem. of behaviour of rock mass, geo-structural AND RECORDED Sh. Sabarna Roy, Sr. Vice President, IN THIS ISSUE OF analysis, determination of support classes and HIMPRABHAT Electrosteel Castings Ltd.and Sh. Rajat monitoring of the section in the process of Chowdhary, Sr. Executive, Electrosteel tackling the squeezing ground condition. This Castings Ltd. in their paper on Ductile Iron topic will help geologists and engineers alike to Pipeline System for Fire Fighting in tunnels

HIM PRABHAT 4 AUGUST 2019 provides the detail structure of ductile iron and cast iron Sh. Javed Hussain Alamgeer, Senior Asstt. Geologist with their properties. This article provides the descriptive KRCL/Sangaldan has given detailed study in his construction and installation techniques of ductile iron article Geological studies of major Bridges at Sangaldan pipeline. In their article, the authors provides guidelines for — 85 & 87. The paper describes the geological jointing of ductile iron pipes, laying of pipelines in trench studies of major bridges at Sangaldan in reliance to and in soft ground which will be very helpful during the encountered geological conditions based on geological installation of fire fighting works in tunnels. logs of Drill Holes along the bridge abutments and Sh. B.K. Sharma, Dy.CE/C/Anji/USBRL Project has geological pit maps prepared after open cutting. The come up with an article on Anji Bridge Adoption of Cable detailed geotechnical investigation is of paramount stayed Bridge. The author has covered details about the importance and will pave way for risk free successful importance of the iconic bridge, its location, brief history completion of projects. and decision to adopt cable stayed bridge. This article Dr. Joginder Singh Consultant Geologist KRCL provides the brief about importance of selection of type of in his article on Geotechnical assessment of the Cracks and bridge for a particular project. Sinking Developed in front of the dumping yard at Buni Stability of slopes is important concern for project in village gives detailed insight about the cause of cracks and Hilly areas. Huge excavation was carried out at Chenab sinking developed due to charging of the area by surface bridge sites to reach at various foundations of Chenab run off and nalla flowing behind the dumping yard. The Bridge. As stabilization measures, large number of cable author covers the detail of remedial measures taken to anchors were installed at Chenab bridge site. Sh. Giri prevent further propagation of cracks. Prakash Bollineni Design Manager, Sh. Venkadesan B. I convey my best wishes to the team USBRL for Business Unit head and Sh. Kannappan Subramanian painstaking efforts in publication of this magazine to Chief operating officer in their paper threw a light on disseminate knowledge amongst experienced and budding Execution of 100T Cable anchors at Chenab Bridge site. professionals alike.

Kundan Adit CONTENTSISSUE XII AUGUST 2019

Tackling Squeezing Ground During Tunnel T1 Rectification of Up-heaved portion of Ballast less Excavation / 16 Track (RHEDA 2000- VOSSLOH 300-1U Methodologies For The Geological And system) laid in Tunnel T-25 on Udhampur-Katra Geotechnical Works During The Construction Section / 37

TUNNELS Of Railway Tunnels In Himalayan Region, Ductile Iron Pipeline System For Fire Fighting India / 28 In Tunnels / 44

BRIDGES Anji Bridge - Adoption Of Cable Stayed Bridge / 58 Execution Of 100t Cable Anchors At Chenab Bridge Site / 65 Geological Studies Of Major Bridges At Sangaldan / 69

INVESTIGATION Geotechnical Assesment Of The Cracks And Sinking Developed In Front Of The Dumping Yard At Buni Village / 94

EDITORIAL EDITORIAL BOARD ASSOCIATE EDITORS CREATIVE EDITORS

VIJAY SHARMA G.S. HIRA B.B.S. TOMAR R.K. HEGDE HUSSAIN KHAN Chief Administrative Financial Advisor & Chief Engineer/North Chief Engineer/ Dy. CE/Design/USBRL Officer Chief Accounts Officer/USBRL Coord./KRCL and SANDEEP GUPTA MATIN AHMED Editor-in-Chief RANDHAWA SUHAG Chief Engineer/South D.P. LAL Secy. to CAO Chief Electrical Engineer/USBRL Executive Director/IRCON CAO/USBRL/JAT PHOTO GALLERY

(Above): Panoramic View of Kohli Adit of Tunnel T-48. (Below): View of Tunnel T-77 D & Piers of Bridge Br-138 PHOTO GALLERY

(Clockwise top from left): View of completed sub structure of Bridge no 43 in Bakkal area on Katra-Banihal section; Reinforcement Binding work at foundation MA2, Anji Bridge near Reasi; DMU train stationed at Qazigund station in Kashmir valley; View From tunnel T-49; Arpinchala Station yard after Snowfall and Excavator work in Tunnel T-77D PHOTO GALLERY HIM PRABHAT 10 AUGUST 2019 PHOTO GALLERY

(Clockwise from left): Panoramic view Chenab Bridge site; casting of foundation of a bridge Br-39; View of piers of Bridge Br-38, Tunnel T-3 in Reasi and Erection of at Chenab Bridge site

AUGUST 2019 11 HIM PRABHAT PHOTO GALLERY

(Clockwise top from left): Fixing of Membrane in a Tunnel T-50; Concreting for bottom Pile Cap of Bridge B.r-43; Approach road to Sumber and Excavation and Mucking in well at Anji Bridge PHOTO GALLERY PHOTO GALLERY

HIM PRABHAT 14 AUGUST 2019 PHOTO GALLERY

(Clockwise from left): Adit of tunnel T-49 in Kundan area; USBRL stall during Rail mela at Ambala and Drilling Main Tunnel T-49A By Boomer (TAM Rock Machine)

AUGUST 2019 15 HIM PRABHAT TUNNELS TACKLING SQUEEZING GROUND DURING TUNNEL T1 EXCAVATION (KATRA TO DHARAM SECTION OF UDHAMPUR-SRINAGAR-BARAMULLA NEW BG RAILWAY PROJECT)

RIELLA A. ABSTRACT: Senior Engineering Geologist, 290 km of Udhampur-Srinagar-Baramulla Rail Link (USBRL) Project is being Geodata SpA. Italy constructed by as National Project in the State of & Kashmir. The Railway Board, Government of India has entrusted the construction QUAGLIO G. of Katra-Dharam (72.91 Km) Section of USBRL project to KRCL through TUNG Director, Northern Railway. A Contract Agreement has been executed between KRCL and Geodata SpA. Italy Northern Railway on 9th August 2005 whereby the design and construction of new BG Rail link from Katra (Excluding) -Dharam (including) between km 30 to SIKKA V. km 100.868 has been entrusted to KRCL and KRCL is executing this project in Civil Engineer, terms of above agreement on behalf of Northern Railway. The works are already in Geodata India Pvt. Limited, progress at various portions of the alignment. As a part of this project under the New Delhi-110038 present tender, it is proposed to award the work for Tunnel Design Consultancy, Site Services and 3D monitoring of Tunnels T1, T2, T3 & T5 between on Katra - ZAMMIT H. Dharam Section of USBRL Project. KRCL has appointed Geodata Engineering Technical Head, S.p.A. for Tunnel Design Consultancy with NATM including rigid support design, Geodata India Pvt. Limited, site services and 3D monitoring of balance tunneling work of the project alignment New Delhi-110038 traverses through the Main Boundary Thrust (MBT) at the lower Himalayas which includes the Siwalik Mudstone Formation Identified as Squeezing prone Ground. This note gives a summary of the regional and local geology at Tunnel T1 location, describes the methodology applied for excavation of the squeezing sections and associated rectification works, followed by recommendations for tunnel excavation in similar conditions.

1. REGIONAL GEOLOGICAL SETTING: By the regional geological point of view, the project is located in the North-western part of the Himalayan Chain and, specifically, in the Lesser Himalaya Zone. The Lesser Himalayan zone is bounded by the Main Central Thrust (MCT) at the North and the Main Boundary Thrust (MBT) at the South (also known in the area as “Riasi Thrust”). The rock units of the Lesser Himalaya are primarily formed by sedimentary rocks belonging to the Indian Platform, involved in a series of anticlines

HIM PRABHAT 16 AUGUST 2019 TUNNELS

and synclines that are in many cases quite sheared, has been shown as active through the Pleistocene (Ni and over-thrust at the South onto the Siwalik Molasse 1984). In fact, most of the accurately located epicenters (Sub-Himalaya zone) along the step NNE dipping of seismic events along the Himalayan arc (78°E-95°E), Riasi Thrust. that occurred between 1961 and 1981, are concentrated The Siwalik Molasse represents a foreland zone in a narrow zone, about 50 km wide, lying between the consisting of clastic sediments that were produced by the northerly dipping Main Boundary Thrust (MBT) and uplift and subsequent erosion of the Himalaya belt, and Main Central Thrust (MCT). deposited by rivers. These young sedimentary formations In turn, the Sub-Himalayas are bounded by a thrust have been folded and faulted to produce the Siwalik Hills fault to the south and are forced over sediments on the that are at the foot of the great mountains. Indian plate. This fault system is called the Himalayan The MBT developed during the Pliocene time, and Frontal thrust (Sorkhabi 1999).

Figure-1: From “Geological map of the Kohistan-Ladakh Western Himalaya region, after Shearle et al. (1999). KKH, Karakoram Highway” (Shearle, 2010).

AUGUST 2019 17 HIM PRABHAT TUNNELS

2. LOCAL GEOLOGY ALONG PROJECT AREA: The geological and structural assessment of the area around the project is clearly described by Fuchs (1972), as reported in Figure 2 and Figure 3. According to the available geological data (Figure 4 and 5), and the recent on field observation (Geodata, March 2012), the area of T1 (new and old alignment) is present the Sirban Group, rocks comprising dolomite with slate bands, thrusted over the Middle Siwalik Formation by the Riasi Thrust/Main Boundary Fault. The first stretch of the tunnel (from T1P1 to about Ch 30 +600) is characterized by the Middle Siwalik Formation that in this area is composed of very soft grey coloured sandstone and siltstones with thin bands of clay shale with boulder conglomerates (Figure 3.6 and 3.7). The Siwalik Formation occupy vast area rising up to an elevation of 900 m and its contact with the overlying Figure-3: Sketch map along Riasi - Gulabgarh section (from Fuchs, 1972).

Figure-2: Section across Kashmir and Chamba (from Fuchs, 1972).

HIM PRABHAT 18 AUGUST 2019 TUNNELS

Figure-4: Tentative geological section along modified alignment of Tunnel-T1

Figure-5: Geological map of the area around Tunnel 1. thrust zone is generally invisible due to thick and (from “Report on geological investigation of Tunnel no. 1 & widespread quaternary cover formed by debris, slope 2 of Katra - Laole Rail Link project of KRCL in Jammu & Kashmir”, by SJVNL 2008). deposits and alluvial soil (Figure 6 and 7). In the central sector the tunnel (from about Ch 30 +600 to about Ch 32+100) crosses the Reasi Thrust and Sirban Dolomite that is about 400m thick consists of sedimentary rock mass mainly composed of (Shivalik Formation) siltstone, claystone, thin beds of sandstone, Angular Fragments of Dolomite with silty sandy clay matrix and Jointed Dolomite with crushed & Sheared Dolomite. Between CH 31+680 to CH 31+780, moderately weathered variegated reddish brown Mudstone with soft infilling /Sheared very soft showing swelling property in presence of water was encountered.

Figure: Error! No text of specified style in document..6: Outcrops of very soft grey colored sandstone - Middle Siwalik Formation.

AUGUST 2019 19 HIM PRABHAT TUNNELS

Figure-6: Outcrops of conglomerates - Middle Siwalik Formation. Figure-7: Alluvial soil - Quaternary formation

Figure-8: Reddish Brown Mudstone at the Thrust Zone. Figure-9: Outcrops of crusched dolomite - Riasi Thrust / Main Boundary Fault

In the final portion the tunnel (Ch 32+100 Figure-10: Outcrops of dolomite in the T1P2 area - Sirban Dolomite Formation to T1-P2) crosses the Sirban Dolomite Formation (Figure 9). The unfossiliferous carbonate rocks form a generally well bedded sequence of light grey to bluish dolomites and limestone. Many forms of stromatolites, intra-formational breccias, oolites, fine laminations and lenticular arenaceous layers occur. Chert lenses and bands, as arenaceus and quartzitic beds are also very common. In the lower part of the series intercalations of dark marls, shale and slates are also described. The thickness of this shallow water sequence is estimated at 1000 to 2000 m. The rocks forming the Sirban Formation are generally hard and highly to moderately jointed with a general trend of bedding oriented NW-SE and dipping 60-65° trough NE. The next section describes the methodology used for the excavation through the squeezing section of Tunnel T1.

HIM PRABHAT 20 AUGUST 2019 TUNNELS

3. DEFINITION OF THE BEHAVIOURAL discontinuities orientation and Geomechanical CLASSIFICATION AND SUPPORT CLASSES: properties are well known; o Evaluation of the rock mass excavation behaviourf u empirical methods which, by quantifying the A quantitative approach developed by Geodata rockmass typical parameters, output indications Engineering, with a high degree of reliability for the on the expected behaviour especially in terms of definition of the behavioral classification is described self-supporting capacity (e.g. Bieniawski’s RMR hereinafter. system). Geomechanical hazards are mainly related to ground The reference classification of the excavation behavior of non-supported excavation, thus taking into behaviour is based on both stress (1) and geo-structural account the intrinsic properties of rock masses and the type analysis (2), with particular reference to the basic associated stress conditions. scheme reported in Figure 11. The matrix that results The forecast analysis for evaluating the response upon from such a double classification approach allows an excavation and then the most probable hazard is optimal focalization of the specific design problem. performed for each rock mass unit necessarily taking into Furthermore, a rational choice of the type of account both stress and Geostructural analyses, as shown stabilization measures may be derived as a function of the in the flow chart shown below. most probable potential deformation phenomenon (→Hazard) that is associated to the different stress and Geostructural combination. Figure-11: General scheme of the excavation behavior according to the GDE Classification. The assessment of deformation response to excavation taking into account the radial deformation at the face δ ( 0) and the ratio Rpl/R0 of different RMU and for the hypothesized stress conditions at tunnel level was carried out by integrating a probabilistic approach with the “Convergence-Confinement Method” (CCM, Carranza- Torres, 2004). As reported in the previous matrix, n.6 categories are defined from the best (“a” class) to the worst condition (“f”) (Russo et al. 1998). More precisely, on the basis of Stresses analysis (1) are based upon a continuum or stress analysis n.4 conditions are identified as a function continuum-equivalent Geomechanical model and are of the cited deformational index and a further mainly aimed at defining classification indexes and subdivision is considered for the special cases of stable expressing the potential intensity of the expected condition (class “a”) and of immediate instability of deformation phenomena. tunnel face (class “f”).

In the common practice quite often “competency” Figure-12: Detailed scheme of the excavation behaviour indexes are being used which represent the ratio between according to the GDE Classification. stress conditions around the tunnel perimeter and the mobilized rock-mass strength (Hoek & Marinos, 2000) or alternatively indexes, based on more developed analytic tools, which directly express the expected behaviour in terms of deformations and/or extent of the plasticized zone, as the one adopted in our analysis. o Geostructural analyses (2) can be broadly grouped NOTES: Russo and Grasso, 2006; δ0=radial deformation at the face (prevalent classification criterion); Rpl/R0=plastic radius/radius of the in two sets: cavity; σθ=max tangential stress; σcm=rock mass strength. In the brittle u limit equilibrium methods, which are normally failure domain, the deformation indices of the stress analysis are not representative and can be taken just as an indicator of the increasing utilized when both rock mass spatial patterns of potential of failure. The limits of shadow zones are just indicative.

AUGUST 2019 21 HIM PRABHAT TUNNELS

Hereafter, the description of the behavioural classes is away from the face the indicative ratio Rpl/R0 is often in reported in detail: the range of 2÷4. It has been observed that this condition is o Behavioural category “a-b”: the strength of the rock frequently rather comparable with the lower limit of Severe mass exceeds the stress level at the face and around the squeezing indicated by Hoek & Marinos (H&M, 2000). cavity. The ground behaviour is elastic and in general o Behavioural category “e”: differs from category “d” with deformations are of negligible magnitude. Instability respect to the magnitude of deformation at the face and phenomena may be only related to wedge failures and this away from the face. At the face δo is greater than 1.0% possibility is low if, for the absence of discontinuities, the while the ratio Rpl/R0 is very high (frequently >4). It has rock mass can be assimilated to a “continuum” (→category been observed that this condition is frequently rather “a”) and high, in the opposite case, if may be related to a comparable with the lower limit of Very severe squeezing “discontinuum” medium (→category “b”). indicated by Hoek & Marinos (H&M, 2000). o Behavioural category “c”: the magnitude of stress o Behavioral category “f”: is characterised by immediate concentrations at the face approaches the strength of the collapse of the face during excavation (impossible to install rock mass. Therefore, the behaviour is elasto-plastic but support). This behavior, not necessarily highlighted by resulting in minor instabilities. The radial deformation stress analysis, is generally associated with non-cohesive soils (δo), defined as the percentage ratio of radial displacement and cataclastic rock masses such as these found in fault at the face (uo) to the equivalent cavity radius, Ro, is zones, especially under conditions of high hydrostatic limited (less than 0.5%). Away from the face, on the pressure and/or high in-situ stresses. periphery of the cavity the stresses exceed the strength of The practical implementation of the described the rock mass, resulting in the formation of a plastic zone classification system in the preliminary design phases, as around the excavation, frequently having a width less than well as during tunnel construction can be reasonably

Ro (i.e. 1

Figure-13: Multiple graph for the evaluation of the excavation behavior and typical potential hazards (Russo, 2008).

NOTE: The Competency Index (IC) is the ratio between rock mass strength (σcm) and the max tangential stress (for circular tunnel and k=1, σθ=2γH, where γ is the rock mass density and H is the overburden). Proceeding clockwise from the left bottom graph (I→IV), the rational scheme applied in the multiple diagram of Figure 8.2 is [in parenthesis the representative property]: TUNNELS

I) Rock block volume [Vb] + Joint Conditions [jC] Rock 10dm3 and slightly undulating, rough joint jC=1.75 → Mass Fabric [GSI] GSI ≈ 50. II) Intact strength [σc] + Rock Mass Fabric → [GSI] Rock II) GSI ≈ 50 and Intact rock strength c=50MPa Rock mass mass strength [σcm] strength σcm=2.8MPa. III)Rock mass strength [σcm] + In situ stress [σθ] → III) σcm=2.8MPa and overburden H=300m → Index Competency [IC] of Competency IC = 0.19 (GD class from stress IV)Competency [IC] + Self-supporting capacity [RMR] → analysis: c). Excavation behaviour [Hazards] IV) IC= 0.19 and RMR =45 → Prevalent hazard wedge It should be noted that the GSI (Geological Strength instability/rockfall → Application of the support section Index) determination in the I quadrant is obtained by type C1. the “quantitative” approach proposed by Russo (2007, For Tunnel T1 squeezing section, based on the above 2009): evidently, the original “qualitative” chart of Hoek procedure, Support Class D which featured installation and Marinos (2000) can be used as well and then to of TH44 deformable steel sets, was recommended. The enter the GSI value directly in the II quadrant. associated excavation and support application sequence is o Rock Classes and definition of support section types given the figure below: Based on the anticipated Rock Mass Behaviour, the appropriate mitigation measures and consequently of the Figure-16: GDE Support Class D Sequence support section types are defined and summarized in support classes as shown in the Tender Drawings for Excavation and Support. In the Table 1, the general criterion of application of the support section types, as a function of the Geomechanical classification of reference, is anticipated, (See Table No. 1 below).

4. TUNNEL T1 - DETERMINATION OF SUPPORT CLASS FOR THE SQUEEZING SECTION BETWEEN CH 31+650 TO CH 31+780: During the excavation, the xx formation was encountered at section CH 31+680 as shown in the Fig 14.3D. Based on the results of probing ahead and geological face mapping, the intact rock, joint condition, and hydrogeological parameters are estimated. The process to determine the required support class during excavation follows the GDE multiple graph as shown in the figure 5. TUNNEL T1 - MONITORING SCHEME FOR below. The GSI is determined based on the volume block THE SQUEEZING SECTION BETWEEN CH and jointing conditions observed on the face. Then, the 31+650 TO CH 31+780: rockmass strength is estimated and the excavation Correspondence between design assumptions, actual competency is evaluated considering the actual ground behaviour and adequacy of new enlarged tunnel overburden at the section chainage. support will be checked during tunnel rectification works Behaviour type is deduced based on expected RMR through the following actions: and finally Support Class and further additional support o Radial displacement monitoring measures are selected from the last quadrant and the o Radial pressure between rock and support monitoring design, (See figure no. 15). o Steel rib deformations monitoring I) Fractured dolomite with Rock block volume Vb ≈ o Force acting in the rock bolt

AUGUST 2019 23 HIM PRABHAT TUNNELS

Table-1: Criterion of application of the support section types

NOTES: The terms for Rockburst and Squeezing intensity are referred to the Canadian Rockburst Support Handbook (CRSH,1996) and Hoek & Marinos (H&M, 2000), respectively. Incidentally, in the specific case of T1 tunnel, the application of the section type C4 it is not foreseen at the present design phase. Figure-14: 3D: Geological Log of the squeezing section at Tunnel T1 TUNNELS

Figure-15: Application of the multiple graph for at the squeezing section in Tunnel T1

Convergence monitoring is the predominant tool to o should be installed in the invert as required and evaluate tunnel stability. Direct observation by according to site Engineer’s instruction, in order experienced construction staff and site geologists is to be to monitor any additional radial pressure from regarded as one essential monitoring activity and needs swelling. to be performed on a continuous basis. The following o No. 5 Strain Meter; instruments should be adopted. o No. 2 (3) Load Cells (to be installed only after rock o Displacement Monitoring Point (DMP; Optical anchors are in their final. configuration, i.e. after Targets for 3D Displacement Monitoring); rebuilding of anchor head assembly). o Pressure Cell (PC): Contact pressure acting on the The following monitoring sections has been steel sets; recommended during the excavation of the squeezing o Strain Meter (SM): Maximum stress in the steel rib; section: (See Figure no. 17). o Load Cell (LC): Maximum force in the bolt head A level action plan is suggested for which specified actions are required should the trigger limit threshold be A typical monitoring array is composed by: exceeded. The data will be downloaded and processed by o No. 7 Displacement Monitoring Point (DMP) or the surveyor for review by the contractor and designer bi-reflex targets, as shown in the figure below; within the day of survey and the data will be reviewed o No. 3 (+1) Pressure Cells (1+1 sidewalls & 1 crown); and evaluated in terms of displacement and convergence one additional pressure cell by the designer against the following limits:

AUGUST 2019 25 HIM PRABHAT TUNNELS

Figure-18: Action Plan Recommended for the Squeezing Section at Tunnel T1

6. CONCLUSIONS AND RECOMMENDATIONS: Figure-17: Monitoring Arrays Recommended for the Squeezing Section at Tunnel T1 Since 1984 GEODATA designed and supervised the construction of over 4,000 km of tunnels and more than 3,300 projects worldwide in: metro, traditional and high-speed railways, roads and motorways, dams and hydroelectric plants, geology and the environment. GEODATA developed a methodology that applies for all kind of ground conditions including difficult ground such as squeezing, typically encountered in fault sections at deep levels. This note described the case of Tunnel T1 excavation through the Himalayas MBT and provided the main steps to tackle excavation in such conditions. A successful excavation starts by a comprehensive geological study and hazards identification followed by a probabilistic prediction of Geo-mechanical hazards (failure types) based on which the support measures and support classes are recommended. Besides, the method includes the GDE multi-graph scheme which is used during design as well as during construction to ensure adequacy of support selection during excavation.

HIM PRABHAT 26 AUGUST 2019 TUNNELS

7. REFERENCES: underground project. Gallerie e grandi opere Hoek E., Kaiser P.K. and Bawden W.F., 1995. sotterranee, N.54, pp.40-51. Support of Underground Excavations in Hard Rock. Russo, G. & Grasso, P. 2007. “On the classification of Balkema, Rotterdam, 215pp. rock mass excavation behaviour in tunnelling”. 11th Hoek, E. & Marinos, P.G. 2009. Tunnelling in Congress of International Society of Rock Mechanics overstressed rock. EUROCK2009. Keynote address. ISRM, Lisbon. Hoek, E. & Marinos, P. 2000. Predicting Tunnel Russo, G. 2009. “A new rational method for Squeezing. Tunnels and Tunnelling International. Part calculating the GSI”. Tunnel. Underground Space 1 - November Issue. 45-51, Part 2 - December 34-36. Technol.24:103-111 Hoek, E., Carranza-Torres, C. T. and Corkum, B. Russo, G. 2014. “An update of the “multiple graph” 2002. Hoek-Brown failure criterion-2002 edition. approach for the preliminary assessment of the Proc. 5th North American Rock Mechanics excavation behaviour in rock tunnelling”. Tunnelling Symposium, Toronto, Canada, Vol. 1. 267-73. and Underground Space Technology n.41 (2014) ITA Working Group n°2, 2015. Strategy for Site pp. 74-81. Investigation. Russo, G., Kalamaras, G.S., Xu, S., and Grasso, P. Palmström, A., 1982. The volumetric joint count - A 1999. Reliability analysis of tunnel support systems. useful and simple measure of the degree of rock mass Proc. 9th International Congress on Rock jointing. IAEG Congress, New Delhi V.221-V.228. Mechanics, Paris. Underground Space Technol; 11: 175-188. Russo. G. 2014. An update of the “multiple Riella A., Vendramini M., Eusebio A., Soldo L., graph” approach for the preliminary assessment 2015. The Design Geological and Geotechnical Model of the excavation behaviour in rock tunnelling. (DGGM) for Long and Deep Tunnels. Springer Tunnelling and Underground Space Technology. International Publishing - Engineering Geology for (41)74-81. Society and Territory - Vol. 6, pp. 991-994. Vannay. J.C. 1993. Géologie des chaînes du Russo G., Kalamaras G.S. and Grasso P., 1998. A Haut-Himalaya et du Pir Panjal au Haut Lahul (NW discussion on the concepts of geomechanical classes, Himalaya. Inde): Paléogéographie et tectonique. Mém. behavior categories and technical classes for an Géol. (Lausanne) 16.

AUGUST 2019 27 HIM PRABHAT TUNNELS

METHODOLOGIES FOR THE GEOLOGICAL AND GEOTECHNICAL WORKS DURING THE CONSTRUCTION OF RAILWAY TUNNELS IN HIMALAYAN REGION, INDIA

AEJAZ AHMAD ABSTRACT: (Geotechnical Expert/PEMS The stability of underground structures is an important aspect during design and Engineering Consultants Pvt construction of tunnels. Depending on the geotechnical conditions and influencing Ltd), factors, different failure modes may be expected, and depending on the potential failure modes and boundary conditions, specific construction measures have to be PRATAP CHANDRA chosen to ensure stability. The most important is developing a realistic estimate of DHANG the expected ground conditions and their potential behaviour/failure modes as a Dy. General Manager/ result of the excavation. The variability of the geological conditions including local C/Geology/IRCON ground structure, ground parameters, stresses and groundwater conditions requires International Limited) that a consistent and specific procedure is used. The main objective of this paper is to present the methods adapted by geologists to determine the ground conditions and use of proper support measures during the construction stage of the tunnel.

INTRODUCTION: The geological mapping procedures used in India are divided into three different stages: (i) round mapping, (ii) systematic mapping and (iii) supplementary studies. The main purpose of round mapping is to obtain geological data for the geotechnical assessment of the rock mass for excavation purposes, especially for the design of tunnel reinforcement. The systematic mapping takes place soon after the roof of the round has been shotcreted. Most of the geological data is gathered during this phase and after the mapping, all observations are measured with specific instrument like Brunton, Clar compass, Schmidt hammer to obtain precise location data. The supplementary studies comprise several mapping phases, which include mapping of the significant fractures (Tunnel Crosscutting Fractures -TCF), detailed mapping and descriptions of deformation zone intersections, as well as petrological and mineralogical sampling. Many of these features are already recognized during the round and systematic mapping, but their detailed definition and description is completed during this last mapping phase. Over time, several improvements have been made to the mapping procedures. The current mapping methods give both detailed information and an extensive view of the geology of the excavated areas. However, the development of the mapping procedure is still undergoing. This paper describes and evaluates the geological and geotechnical mapping procedures used in the railway tunnels in Himalayan region.

HIM PRABHAT 28 AUGUST 2019 TUNNELS

Figure 1: The geological map of the USBRL Project. Note the railway stations of the Jammu-Udhampur-Srinagar-Baramulla rail alignment are marked on the map.

AUGUST 2019 29 HIM PRABHAT TUNNELS

When the project alignment traverses through regions Boundary Thrust (MBT) or Murree Thrust in the south with full of geological surprises (geological features, such and Main Central Thrust (MCT) or Panjal Thrust in the as faults, tectonic mélanges, hidden channels, etc. which north. The succession of the Lesser Himalaya comprises remains unnoticed during preliminary survey) and Proterozoic and Cambrian sedimentary and meta- continuous changing geology, as in Himalaya or in Alps, sedimentary rocks. The Higher Himalaya is separated it is appropriate to adopt the approach known as from Lesser Himalaya along MCT and consists of ‘observational method’, in which the design can be sedimentary, low-to high-grade metamorphic rocks of reviewed during construction after interpreting Paleoproterozoic to Ordovician. The Higher Himalayan monitoring data (geological, geotechnical, Crystalline passes into the Tethyan Himalayan Sequence geomechanical, etc.). For this geologists and geotechnical towards north along South Tibetan Detachment (STD) engineers play significant role. The alignment of the and comprises sedimentary sequence and igneous rock of Udhampur-Srinagar-Baramulla Rail Link (USBRL) Proterozoic to Cretaceous-Eocene age. On the extreme Project passes through the Himalaya (Lesser and Higher) north, Indus Tsangpo Suture Zone (ITSZ) is represented situated in Jammu and Kashmir. An observational by ophiolite sequence indicating presence of Neo- approach known as New Austrian Tunnelling Method Tethyan Ocean. (NATM) has been adopted for the construction of tunnels in this new Udhampur-Srinagar-Baramulla Rail DETERMINATION OF GEOLOGICAL Link (USBRL) Project. USBRL Project is a project of CONDITION : national importance and is under the supervision of Tunnelling is an underground work, where the rock or Northern Railway (NR). NR deployed Ircon soil, generally termed as ‘ground’ is considered as the International Limited and Konkan Railway Corporation main construction material for the tunnel, therefore the Limited (KRCL) for execution. Under whom several initial or natural strength of the ground has to be executing agencies and Detail Design Consultancies preserved (Deere et al., 1967). (DDC) are working. It is the geologist who understands the ground and its behaviour and how the ground will react during GEODYNAMICAL SETTING OF PROJECT AREA: excavation process. To understand and to document The entire region is characterized by highly immature these, the geologist used to perform the followings and rugged topography with high relative relief described below. influenced by active erosional processes of Himalayan Rock mass is rarely continuous, homogeneous and Rivers. The valleys are ‘V’shaped, often featured by very isotropic, and is usually dissected by several discontinuity gentle slope on their higher levels, whereas lower levels planes (fractures, cleavage, joints, etc.) and other are narrow ‘V’ shaped and terminates into narrow gorges structures, especially in the geodynamical setting in the lowermost levels. The evolution of Himalayan described above (Fig. 2). Mapping of such elements is an mountain chain began when Indian Plate collided with essential component for the design of underground Eurasian Plate, after its detachment from Gondwanaland excavation. Different engineering geological parameters, and buckling of sediments which were deposited in such as, weathering/alteration, structure, colour, grain Tethyan Ocean(GSI, 2005; DeCelles, 2001; An Yin, size, rock type, groundwater influence, details of 2006). Mountain range is subdivided into four principal discontinuities (number of joint sets, orientation, tectonic zones, namely, (1) Sub-Himalaya (or Foreland persistence, spacing, aperture/thickness, infilling, Zone), (2) Lesser or Lower Himalaya (or Autochthonous waviness and unevenness), etc. are used to be collected. Fold Belt), (3) Higher or Greater Himalaya Crystalline Geologists used to determination actual ground type (or Nappe Zone), and (4) Tethyan Himalaya ( ). Sub- (GT), assessment of the system behaviour in the Himalaya is bounded by Main Frontal Thrust (MFT) in excavation area (GBT), determination of excavation and the south and Main Boundary Thrust (MBT) or Murree support (following the design given by DDC), check of Thrust in the north; it consists of Tertiary to Quaternary the system behaviour and geotechnical safety sediments. Lesser Himalaya is bounded by Main management. Geologists used to prepare the reports or

HIM PRABHAT 30 AUGUST 2019 TUNNELS

do documentation on daily basis on the format provided of joints and tunnel axis to depict whether the tunnelling by DDCs of respective tunnels. The documentation is in favourable direction or not, (f) taking note of how format involves three sheets (excluding the photographic much seepage is occurring. documentation sheet), namely, (1) Tunnel Face Mapping Sheet (TFMS), (2) Rock Mass and Support Section (RMSS), and (3) GSI Index Estimation (GSIE). The Figure 3: Representative face log showing different rocks and format used to document the geological and geotechnical geological features. Each square is of 1X1 m. condition of the tunnel face is similar and uniform in all tunnels Project. Face logging on the scale of 1:100, involves mapping of geological information on the excavated tunnel face (Fig. 3). It includes: (a) identification of rock or ground types (RT or GT), (b) identification of geological structures, like foliation, joints, bedding planes, faults, folds, etc., (c) measurement of orientation of geological structures by compass, those are strike, dip, plunge, etc. of linear as well as planar features, (d) marking of special features on face, such as, shear seams, quartz veins, etc., (e) Proper marking of seepage areas on face, (f) taking note of geological over breaks due to conjugate joints (wedges), decomposed rock-mass and/or water. uniaxial compressive strength (UCS) by following the method of ISRM, (c) determination of weathering grade by ISRM method , (d) measurement and calculation of rock quality designation (RQD), (e) using of orientation data

Figure 2: Representative face where different geological features are marked

AUGUST 2019 31 HIM PRABHAT TUNNELS

RATING THE ROCK-MASS ASSESSMENT OF GROUND BEHAVIOR After taking note on every aspect mentioned above, the After determination of RT(Rock type) or GT(Ground rock mass has to be classified according to the rating. type), size and shape of potential wedges in rock mass The utilities of rock mass classification are: (a) to divide a surrounding an opening have to be determined.The particular rock mass into groups of similar behaviour, structural geological data (dip amounts and directions of (b) to provide a good basis for understanding characters joints and bedding planes/foliation planes, etc.) collected of each group, (c) to identify most significant parameters have been plotted on spherical projections (stereonet) influencing the behaviour of rock mass, (d) to facilitate (Fig. 4). Kinematic analyses of the joint data have been planning and design of structures in rocks by yielding done to predict the stability of the blocks. Also, the quantitative data required for the solution of engineering orientation of the tunnel and influence of orientation of problems. There are different classification schemes joints on this opening have to be analysed by using which are adopted all over the world (Terzaghi’s rock UNWEDGE software. The stereonet plot of these data mass classification, Stand-up time, Rock Mass rating would also be used to identify the wedges and the (RMR), Rock Tunneling quality index (Q), Rock Mass stability of the face. The software are also been used for Index (RMi), Geological Strength Index (GSI)(Barton et identifying and analyzing the character and behaviour of al., 1974; Bieniawski, 1973; 1989; Hoekand Brown, the wedges that would develop due to conjugate joints. If 1997; Palmstrom, 1995; Russo, 2014). All these schemes required, the same software would also be used to involve degree of fracturing in the rock mass as the main determine the rock-bolting pattern to protect the slide input parameter. prone wedges (Fig. 5). The hazards involve swelling, For calculation of RMR, six parameters would be squeezing, crown failure, face instability, invert heaving, taken, i.e., uniaxial compressive strength of the rock, etc. The failure of rock mass around underground Rock Quality Designation (RQD), groundwater opening depends upon in-situ stress level and conditions, spacing, conditions and orientation of characteristics of rock mass. In-situ stress depends upon discontinuities. Then GSI is used to be calculated, i.e., overburden pressure and tectonic pressure. RMR’-5.For determination of Q-value, the following Behavioural category “A”-Strength of rock-mass equation would be used: Q= (RQD/Jn) X (Jr/Ja) X exceeds stress level at face and around the cavity. Ground (Jw/SRF); where, RQD=Rock Quality Designation; behaviour is elastic and negligible magnitude of Jn=Joint set number; Jr=Joint roughness number; deformation. Wedge failure seldom occurs. Ja=Joint alteration number; Jw=Joint water reduction (ii) Behavioural category “B”-Same as “a”, but instability factor; SRF=Stress reduction factor.The available Q-value phenomena are associated with wedge failure. then plotted on a logarithmic graph paper for classifying Figure 4: Stereonet projections used to determine the wedges and the rock mass accordingly. RMR uses compressive the probability of the wedges to fail. strength directly while Q only considers strength as it relates to in-situ stress in competent rock. GSI has been used here to properly demarcate the geo-mechanical properties of the rock mass, starting from intact rock, taking into consideration the discontinuity network and the relative geotechnical characteristics. The available GSI value would then be plotted in a chart. In this present project emphasis has been given on RMR and GSI; however, Q-values are often calculated from RMR also. Due to some inherent advantages of RMR and GSI over Q (joints and their orientations with respect to tunnel orientation are considered in RMR), to classify the support system at tunnels in the Himalayan region, all DDCs have adopted RMR and GSI (Table 1).

HIM PRABHAT 32 AUGUST 2019 TUNNELS

Table -1

(iii) Behavioural category “C”-Magnitude of stress On the periphery of the cavity the stress exceeds concentrations at face approaches strength of rock-mass. strength of rock-mass, resulting in formation of plastic Behaviour will be elasto-plastic and minor instabilities zone around excavation having width less than radius of will occur. the tunnel. (iv) Behavioural category “D”-Magnitude of

AUGUST 2019 33 HIM PRABHAT TUNNELS

Figure 5: UNWEDGE Software used to predict the wedges and stability. Note the Factor of Safety on the right side column condition.(vi) Behavioural category “F”-Characterized by immediate collapse of the face (impossible to install support). Behaviour associated with non-cohesive soils and cataclastic rock-masses (fault zone), under high in-situ stresses.

DETERMINATION OF GROUND CONDITION AHEAD Advance probing of 12 to 25 m are often carried out to determine the geological condition ahead. During advance probing, joint measurements and collection of data (torque, penetration rate, type of out-coming rock chips and colour of water, etc.) with contractor and DDC representatives.However, at each of the tunnels in USBRL Project, the escape tunnel (ET) with smaller diameter is ahead of the main tunnel (MT), hence advance probing is not so required. If the strike of the stress concentrations at face exceeds strength of the rock mass is perpendicular to the tunnel orientation, rock-mass. Face will be in plastic zone. Though the then the ground condition encountered at ET definitely deformation gradient is low, therefore, immediate comes in MT. If the case is not so, then advance probing collapse of the face will be prevented. There will be are used to be done. Even at a few tunnels in this project development of plastic zone around the cavity results in Tunnel Seismic Prediction (TSP) has also been used to worse stability conditions overall. (v) Behavioural know the ground condition ahead.And finally 3D map category “E”-Stress to strength state results in high and longitudinal section are used to be prepared from deformation gradient which causes critical conditions of the face logs to show the geological variation (expected face stability. Width of the plastic zone is greater than and actual geological condition) along the tunnel path tunnel radius. This category includes highly squeezing (Fig. 6).

Figure 6: The longitudinal geological section of the tunnel.

HIM PRABHAT 34 AUGUST 2019 TUNNELS

DEFINING APPROPRIATE SUPPORT SYSTEMS and other instruments like extensometer, strain gage, The design of the tunnels is based on New Austrian pressure cell, etc. are also used. Tunneling Method (NATM), which is based on a concept whereby the ground surrounding an CONCLUSION underground opening becomes a load bearing The geological assessment of the ground during the structural component through activation of a construction stage of the tunnel is significant, ring-like body of supporting ground (Rabecewicz, 1964; especially in the diverse and ever changing geology 1965; Muller and Fecker, 1978; Austrian National of the Himalayas. Geological assessment involves Committee of ITA, 1980; Karakus and Fowell, 2004). geological mapping of different rocks and the NATM also known as Sequential Excavation Method discontinuities present, the prediction of rocks’ (SEM) works on understanding of the behavior of the behaviour during the excavation, application of proper ground as it reacts to the creation of an underground supportive measures to tackle the adverse behaviour of opening. The cross-section of the tunnels is generally the rock and also the assessment of deformation after modified horse-shoe shape to promote smooth stress support installation, if any. There are different redistribution around newly created opening. stages of geological mapping, which were described Primary support (shotcrete, lattice girder and rockbolts) earlier. Here the emphasis has been given to the face allowed a controlled ground deflection to mobilize logging which are generally done soon after the inherent shear strength in the ground and to initiate excavation. At least three hours of time of mucking load distribution. after the blast are used to do geological mapping, Considering geomechanical parameters and in-situ assessment and evaluation of the support which will be stress depending on overburden, appropriate support provided after mucking. If the ground condition in classes have been defined (classes varies depending upon actual differs from the ground condition predicted, the the designers), which is made possible by considering support system also used according to the ground precedent experiences in other similar tunnels. Supports condition, the support class gets changed. The face are further verified by Confinement-Convergence logging and rock mass rating methods which are in use at Method (CCM) and numerical models. Based on the the railway project in Himalayan region have been ground characteristics (RT or GT) and the determined described here. The RMR and GSI are in use for rock ground behaviour (RBT or GBT) a feasible construction mass classification and deduction of support system concept is to be chosen, consisting of excavation method, accordingly. Other methods like analysis of wedge excavation sequence, support measures and auxiliary stability, relationship between major joint and tunnel methods. The tunnelling concept in general contains: orientations, determination of geological condition (a) Ground improvement methods, (b) Dewatering ahead, etc. are also described. Based on which the methods, (c) Excavation methods, (d) Excavation and instability phenomena like wedge failure, spalling, support sequence, (e) Pre-supports, (f) Support rockbursting, squeezing, etc. are predicted. concept, (g) Possible round length. Therefore after proper Accordingly the engineers provide the appropriate rock mass classification and identification of behaviour, supportive measures, so as to do tunnelling safely. the appropriate support class determined for that Therefore geologists and geotechnical engineers are particular ground condition are used to be provided. To important in understanding and determining the evaluate the deformation in the provided support system, ground condition and the required support systems, tunnel instrumentation and 3D monitoringare used to be especially in this observational method (NATM) of done, for which bireflex targets as Deformation tunnelling. The methodologies described in the paper Monitoring Points (DMP) were installed in the tunnel are very simple and compact and are very useful during roof and at selected points along the tunnel walls (5 to 7 the tunnelling process through this young notorious in a section). Himalayan mountain belt. These data acquiring Vertical, horizontal, and longitudinal (in tunnel methods are quite safe and are helpful in proper direction) movements were measured from the targets determination of supports.

AUGUST 2019 35 HIM PRABHAT TUNNELS

REFERENCES o Geological Survey of India (2005): Geological o An Yin (2006): Cenozoic tectonic evolution of the map of Himalaya, the Director General, Geological Himalayan orogeny as constrained by along-strike Survey of India variation of structural geometry, exhumation o Hoek, E, and Brown, E T, 1997. Practical history and foreland sedimentation, Earth Science estimates of rock mass strength. International Reviews, 76, pp. 1-131 Journal of Rock Mechanics and Mining Sciences, o Austrain National Committee of ITA (1980): The 34(8) New Austrian Tunnelling Method, Definition and o Karakus, M. and Fowell, R.J. (2004): An insight Principles", Selbstverlag der Forschungsgessellschaft into the New Austrian Tunnelling Method fur das Strassewwesenim OIAV, Wien (NATM), ROCKMEC?2004-VIIth Regional Rock o Barton, N, Lien, R, Lunde, J, 1974. Engineering Mechanics Symposium, Sivas, Turkey classification of rock masses for the design of tunnel o Müller, L. and Fecker, E. (1978): Grundgedanken support. ??Bieniawski Z T, 1973. Engineering und Grundsätze der Neuen Österreichischen classification of jointed rock masses. Trans S Tunnelbauweise” - “Basic ideas and principles of the AfrInstCivEng 15:335-344 New Austrian Tunnelling Method” In: Trans Tech o Bieniawsky, Z T, 1989. Engineering rock mass Publications, pp. 247 - 262 classification: a complete manual for engineers and o Palmstrom, A, 1995. Characterizing the strength geologists in mining, civil and petroleum of rock masses for use in design of underground. engineering, Wiley-Interscience publication. o Rabcewicz, L. (1964): The New Austrian Tunnelling o DeCelles P.G., Robinson D.M., Quade J. and Method, Part One, Water Power, p. 453-457, Part Ojha T.P. (2001): Stratigraphy, structure and Two, Water Power, p. 511-515 ??Rabcewicz, L. tectonic evolution of the Himalayan fold-thrust belt (1965): The New Austrian Tunnelling Method, Part in western Nepal, Tectonics, 20, pp. 487-509 Three, Water Power, p. 19-24 o Deere D U, Hendron, A J, Patton, F D, Cording, o Russo, G, 2014. An update of the “multiple graph” E J, 1967. Design of surface and near surface approach for the preliminary assessment of the construction in rock, proc. 8th U. S. symp. Rock excavation behaviour in rock tunneling. Tunneling Mech., AIME, New York and Underground Space Technology

HIM PRABHAT 36 AUGUST 2019 TUNNELS

RECTIFICATION OF UP-HEAVED PORTION OF BALLAST LESS TRACK (RHEDA 2000- VOSSLOH 300-1U SYSTEM) LAID IN TUNNEL T-25 ON UDHAMPUR-KATRA SECTION, UNDER RUNNING TRAFFIC CONDITIONS, BY EMPLOYING AN INNOVATIVE NON-DESTRUCTIVE METHOD USING SPECIALLY DESIGNED VOSSLOH 300-1U FITTINGS

1 PREFACE This paper gives an insight into the unique and innovative work of rectification done to solve the longstanding problem of an upheaval existing in ballastless track (RHEDA 2000- VOSSLOH 300-1U system) laid in Tunnel No. T-25 located between Udhampur and Katra section of USBRL Project. This rectification work was unique in nature for the reason, being the first of its kind executed in a ballastless track SANDEEP GUPTA under operation on Indian Railways, which has not yet been done Chief Engineer, anywhere so far. The rectification work involved flattening of up-heaved South USBRL portion of BLT by introduction of a properly designed vertical curve of 1 in 4000 radius in the track structure without any destruction to the permanent concrete structure. For providing a vertical curve of 1 in 4000 radius in track structure, special fittings from VOSSLOH 300-1U Germany involving height adjustment steel and plastic plates , angled guide vanes etc were got designed ,imported and installed in order to introduce the designed vertical versine under each rail seat. This entailed precise survey of rail levels, data collation and plotting, design SUMEET KHAJURIA of best fitting vertical curves (Radii more than 1 in 4000) over the Deputy Chief Engineer design track length and working out vertical versines for each rail seat Sangaldan and accordingly design ,manufacture and install height and gauge adjustment plates underneath each rail seat for execution. The entire work was planned and successfully executed under three traffic block of 4 hours duration each, taken for three (03) days in all. After installation, fittings were tightened for the design torque 250 N-m to achieve the designed service track parameters for gauge, cross level, twist, unevenness and longitudinal rail levels. Speed was relaxed in stages before finally a joint speed trial was done with open line to check ANIRUDH BANSAL the riding comfort over the rectified track length. No abnormality was Executive Engineer noticed and speed was thus relaxed to sectional speed of 80 kmph on Katra 05.04.2019.

AUGUST 2019 37 HIM PRABHAT TUNNELS

2 ORIGIN OF PROBLEM options to address the problem were zeroed 2.1 Tunnel T25 is a 2.5 km Length tunnel, in on: constructed in the year 2005. Ballastless Track a) Option 1: Destructive method: Dismantling (RHEDA 2000- VOSSLOH 300-1U system) of the 13.3 m upheaved track structure designed by RAILONE Germany was laid inside and re-casting with in-situ concrete. This tunnel in the year 2012- 2013. This tunnel, involved a block period of 21 days i.e. located between Udhampur to Katra, was stoppage of all traffic between Udhampur- thrown open to passenger traffic in July’ 2014, Katra for three weeks. as a part of railway line opened between b) Option 2: Non-Destructive method: Udhampur to Katra. Introduction of a properly designed vertical 2.2 In Feb 2015, an unusual phenomenon of curve of 1 in 4000 through installation of upheaval of ballastless track occurred between specially designed modified vossloh fittings Ch. 66.00- Ch. 66.01 inside T25 during for each sleeper for the length of the design ongoing grouting work in the tunnel for tunnel curve. This involved its execution under 5-6 strengthening and seepage rectification. blocks of 4-5 hrs each. 2.3 Grouting operation was immediately stopped 3.2 Option (2) was considered as practical and and relief holes were drilled inside drains so as workable solution keeping in view that the to dissipate the locked up pore water pressure in work was to be executed under running clayey substratum, if any, formed during traffic conditions. grouting. As a safety measure, a speed restriction of 20 kmph was immediately imposed over the 4 DESIGN AND PLANNING affected length to ensure safe running of trains. 4.1 As per the maintenance manual for RHEDA 2.4 It was observed that due to locked up uplift 2000 slab track system, lateral adjustments up pressures, an upheaval of 95 mm occurred to +/-8mm per each fastening and height in the permanent structure (BLT) evenly spread adjustments up to -4mm/+56 mm can be made over 13.3 m length of the ballastless track. As a up with variable vossloh 3001-U fittings. As this result of this upliftment, track parameters rectification work involved upheaval adjustments (Gauge, cross levels, longitunal level, twist and greater than the prescribed limits, RAILONE gradient) were checked and found distorted of Germany being original system provider for its service limits. RHEDA 2000 BLT, was engaged for seeking 2.4 Speed restriction of 20 kmph continued till a design of vertical curve (1 in 4000) with special permanent solution to the problem was found modified fittings. and implemented. However to monitor any 4.2 Precise survey, data collection using digital further deterioration in the track parameters due autolevel and total station was done for left to running of trains , measurement of track hand and right hand rails and survey data was parameters was regularly done for 3 years and plotted for profile sketch (Exhibit: 1). recorded to notice residual active movements if 4.3 Based on the design, three Verticle curves having any .It was observed that the hump had steadied radii greater than 1 in 4000 were designed for with no movements noticed at any stage post smoothening of upheaved portion thus entailing occurrence in 2015. total track length of 100 mtrs (166 sleepers) (Exhibit: 2). 3 POSSIBLE SOLUTIONS TO THE PROBLEM 4.4 Shimming pattern was calculated under each rail 3.1 To address the problem, rounds of discussions seat for the designed vertical curves. For were held with the available engineering experts manufacturing, specially designed height in the field of BLT design for arriving at a adjustment plates of steel plates (Ap 20s) of practical solution for repair of the hump. Two thickness 20mm, Plastic height regulation plates

HIM PRABHAT 38 AUGUST 2019 TUNNELS

(Ap 20u) of 6mm and 10mm, Rail pads 5.4 Sleeper screws were opened using spanners and (Zw692) varying 2mm to 12 mm were Rails were lifted using Manual jacks. Rail seat designed. Gauge adjustment was done through was cleaned, already installed fittings were taken angle Guide Plates (Wfp 15U) of varying width. e out and modified fittings were seated under Dowel Screw (Ss 36) length of increased length each rail seat as per the shimming and were designed and manufactured to cater regulation sheet. The work was completed in increased height adjustments . (Exhibit: 3). two days and then sleeper screws were tightened 4.5 Detailed shimming and regulation sheet was using torque wrench of design torque to prepared for various track components for the maintain track parameters.Track parameters designed track length. (Gauge, Cross levels, longitudinal rail levels etc) 4.6 After finalisation of the Shimming list and were measured and found within prescribed regulation sheet, manufacturing of these service limits.The entire work was done in the modified fittings was done in Germany, presence of Open line (Exhibit :5). and India, before they were finally imported to 5.5 Track profile plotted pre and post rectification India and transported to site of the work. work is placed at Exhibit: 6. 5.6 Speed Relaxation was carried out in stages of 30 5 TEAM MOCK UP AND WORK EXECUTION kmph and 45 kmph before a final joint speed 5.1 Fittings designed as per regulation sheet were trail was done in conjunction with open line to enumerated assembled and synchronized as per relax the speed restriction to sectional speed of the sleeper no. and were placed on both sides of 80 kmph. The joint speed trail done was the sleepers. successful and no abnormality was noticed. 5.2 A Mock up trail for replacement of 5-6 fittings with modified ones was carried out on 17.01.19 6 CONCLUSION under traffic block so as to determine its fitment As Indian Railways is fastly moving from ballasted at site.(Exhibit: 4). to slab track system , this kind of non-destructive 5.3 Execution of Replacement work was planned to rectification work done has added a new dimension be done under a traffic block of four hours towards the maintenance and repair work of BLT , which (12.00AM to 4.00 AM) taken for 3 days each can be done under running traffic conditions for such w.e.f 20.01.19 to 22.01.19. peculiar problems.

AUGUST 2019 39 HIM PRABHAT TUNNELS

Exhibit 1: Upheaval profile (Left hand and right hand rail)

Exhibit 2: Design curves TUNNELS

Exhibit 3: Modified Vossloh fittings 300-1-U

Modified fittings 300-1-U seated

AUGUST 2019 41 HIM PRABHAT TUNNELS

Exhibit 4: Mock Up trail

Exhibit 5: Work Execution under traffic block

HIM PRABHAT 42 AUGUST 2019 TUNNELS

Exhibit 6: Track profile (Pre and Post rectification)

AUGUST 2019 43 HIM PRABHAT TUNNELS

DUCTILE IRON PIPELINE SYSTEM FOR FIRE FIGHTING IN TUNNELS

1 PREAMBLE: Electrosteel products have been tested as per the protocol of Burning Test on March 31, 2014 by the INSTITUTE FOR FIRE PROTECTION TECHNOLOGY AND SAFETY RESEARCH COMPANY M.B.H, an accredited testing, inspection and certification body in Austria and have cleared them for tunneling chimney preparation in accordance with ONORM EN 1363, Part I and RVS 09.02.24 /EN 13501-2. The piping system was flooded SABARNA ROY 300 liter/minute, which simulates a water removal in the event of fire. As such, Senior Vice President Electrosteel Ductile Iron products are suitable for fire-fighting works. (Business Development), Electrosteel Castings Limited MOLECULAR STRUCTURE OF DUCTILE IRON AND CAST IRON: In CAST IRON, graphite is present in plate like flakes which are a source of inherent weakness. Under heavy shock loads, cracks spread along the flakes making CI brittle.

RAJAT CHOWDHURY Senior Executive (Business Development), Electrosteel Castings

Graphite structure is changed by adding Magnesium: In DUCTILE IRON, shape of graphite structure becomes a spheroidal nodule. This nodular shape increases tensile strength and gives elongation property by preventing spreading of cracks.

Corrosion and Corrosion Protection Systems relevant to Ductile Iron and Mild Steel Pipelines: In Ductile Iron pipes, the Carbon content is approximately 3.5%. The Carbon is present in the form of nodules / spheroids. Because of the high presence of Carbon, which imparts a discontinuity in the ferritic matrix,

HIM PRABHAT 44 AUGUST 2019 inherent corrosion resistant properties are imparted to Ductile Iron. The Carbon nodules / spheroids impede the progress of oxidation in the ferritic WHAT IS DUCTILE IRON? matrix. In Mild Steel that is used for manufacturing of Mild Steel pipes, the Carbon content is approximately 0.3%, which is around 12 times lower than CROSS SECTIONAL VIEW OF DUCTILE IRON PIPE: that of Carbon present in Ductile Iron. This is the reason why Mild Steel is inherently corrosion prone and requires extensive corrosion protection systems. In spite of the inherent corrosion resistant properties of Ductile Iron, Ductile Iron pipes are supplied with extensive corrosion protection systems, both inside and outside so that the pipes can have a very long life at a marginal increase in cost.

FLOW CHART OF PROCESS/TEST: TUNNELS

PROPERTIES OF DUCTILE IRON PIPES:

BARREL WALL THICKNESS, OPERATING PRESSURE AND SITE TEST PRESSURE AS PER IS: 8329 - 2000:

HIM PRABHAT 46 AUGUST 2019 TUNNELS

JOINTS - SOCKET & SPIGOT TYPE: Pipe sealing arrangement: Diagram of a Socket and Spigot Push-on Joint:

The Rubber Gasket insulates one pipe from the other and prevents electrolytic corrosion in the pipeline.

Gaskets for Ductile Iron Pipes: Gasket is one of the major components which ensure proper functioning of joints. PUSH-ON JOINT: Gaskets are supplied as per IS: 5382 - 1985 (amended in May 2002) - Specification for Rubber Sealing Rings for Gas Mains, Water Mains & Sewer Lines. Rubber gaskets used for jointing of DI pipes are constructed by fusion bonding two types of rubbers having different hardness (normally 40-50 Shore at the bulb and 80 Shore at the heel). The hard rubber is used to construct the heel or the anchor section of the gasket while the soft rubber is used to build the sealing bulb. Actually, the internal pressure is applied to the bulb portion of the rubber gasket (which acts as the seal against leakage) while the exerted force is counteracted by the stronger heel portion of the gasket. It has been found out that when the internal pressure is applied the compressed rubber gasket tries to regain its bulb shape, which makes the joint tighter, thus ensuring Pressure holding & Leak- proofing: 100% leak tightness.

EPDM (Ethylene Propylene Diene Monomer)

AUGUST 2019 47 HIM PRABHAT TUNNELS

Type Test of Joints:

LEAK TIGHTNESS OF JOINTS TO POSITIVE AND o Joint assembled with gasket and a shear load is NEGATIVE INTERNAL PRESSURE: applied on the spigot end. o Spigot end is machined to minimum. o Joint is tested at a higher pressure than the works test o Socket opening is machined to maximum. pressure with and without joint deflection.

Type Test Results (under the supervision of British standards institute):

Gaskets for Ductile Iron Pipes- Aging: In the case of socket joints, the seal is obtained The change in the mechanical properties of elastomers with time by the contact pressure between the metal and can be indicated by two phenomena: gasket. The elastomer deformation produced o Creep (increasing deformation under constant loading). during jointing remains constant. The relaxation o Relaxation (compression relaxation under constant deformation). phenomenon is therefore the only one of interest.

HIM PRABHAT 48 AUGUST 2019 TUNNELS

Relaxation measurement: o one saddle per pipe, o each support behind a socket, o a support saddle (α=120° is a good precaution), o a fixing clamp with rubber lining.

Thermal expansion The advantage of ductile iron pipelines is that they do not require the installation of expansion absorbers. Fixed point: every clamp must be sufficiently secured to constitute a fixed point (use a clamp of adequate width). Expansion accommodation: the push-in joint between each support acts as an expansion absorber, taking up the expansion of the pipe length (within the permissible limits of ΔT).

Relaxation of elastomers is determined by a procedure which measures the change with time of the force required to compress a specimen of fixed deformation. The previous diagram shows the relaxation at ambient temperature of the EPDM used in the joints of Ductile Iron Pipes used for potable water supply & irrigation system. Anchoring PIPE LAYING ABOVE GROUND: Any component subjected to hydraulic thrust (bends, Laying of a Pipeline above ground involves determining: tees, tapers) must be stabilized with an anchor block. o the support system, the accommodation of thermal expansion, the anchorage of components subjected to hydraulic thrust.

Supports The following points are usually followed when laying pipes above ground.

AUGUST 2019 49 HIM PRABHAT TUNNELS

o Directional changes involving large radius bends can Thermal expansion be negotiated simply by joint deflection (within the The advantage of ductile iron mains is that expansion specified limits). In this case, care must be taken to absorbers are not necessary. reinforce the saddle anchorage of pipes involved, Fixed point: every clamp must be sufficiently secured having assessed the hydraulic thrusts at the deflected to constitute a fixed point (provide a clamp of joint positions. sufficient width). o Provision of an adequate safety margin on the Expansion accommodation: the push-in joint between support dimensions (saddles and clamps) is each support acts as an expansion absorber, taking up the recommended, to compensate for hydraulic forces expansion of the pipe length (within the permissible due to any misalignment of the pipes. limits of ΔT).

PIPE LAYING THROUGH TUNNELS: Laying a socket pipe system through a tunnel involves: o support, accommodation of thermal expansion, anchorage of components subjected to hydraulic thrust. Ductile iron socket pipes provide a simple solution, particularly if cramped conditions do not permit the use of large joint assembly equipment.

Supports Anchoring o one per pipe, Every component subjected to hydraulic thrust o each support behind a socket, (bends, tees, isolating valves) must be stabilized by an o a support saddle (α=120° is a good precaution), anchoring system (rigid welding to fixing plates is often a o a fixing clamp with rubber lining. good method). Directional changes involving large radius bends can be achieved simply by joint deflection (within the specified limits). In this case, care must be taken to reinforce the support anchorage of the pipes involved, having assessed the hydraulic thrusts at the joint positions. It is recommended to include a safety coefficient, to compensate the hydraulic forces due to a possible misalignment of the pipeline.

HIM PRABHAT 50 AUGUST 2019 TUNNELS

PIPE LAYING - STEEP INCLINE: Anchoring with anchored joints Laying of ductile iron mains on steep inclines can be This technique is quite suitable for pipes laid below performed in two ways: ground. o using concrete blocks for each pipe, using a concrete It consists of anchoring a section of anchored pipes: block at the head of an anchored o either by an anchor block situated behind the socket of the leading pipe, Axial Force o or by an additional anchored length (L) installed in Beyond a certain angle, the friction between a main and the flat section behind the uppermost bend. the ground is insufficient to hold the main. The The maximum axial force is supported by the first longitudinal gravitational movement then has to be anchored joint below the block. This force is a function counteracted by the use of anchor blocks or anchored of the gradient, and also of the length of the anchored joints, or a combination of both techniques. In simple section. The maximum permissible length therefore is terms, it is found that a main needs to be anchored when defined by the strength limit of the anchored joint. the incline exceeds: 20 % for a surface main & 25 % for NOTE: (1) If the length of the incline exceeds the a buried main. permissible anchored length, the descent can be made in several independent sections, each being anchored at its Anchoring every pipe head with a concrete block. The end joints of the This technique is quite suitable for surface mains. sections are not anchored in this case. o An anchor block behind every pipe socket. (2) The main must be laid downhill starting from the o Sockets point uphill to take purchase on the blocks. highest point, so that the self-anchoring system is fully o A clearance of 10 mm is left between the spigot engaged and tensioned. end and the back of the socket chamber to accommodate expansion.

AUGUST 2019 51 HIM PRABHAT TUNNELS

Anchoring Block Dimensions for a Buried Section SUPPORTING PIPES ABOVE GROUND: a: height of the block heel a: gradient Socket and Spigot Pipes F: slip force It is recommended that above ground installations of L: seating length spigot and socket pipes be provided with one support per B: seating width pipe, the supports being positioned behind the socket of H: block height each pipe. W: weight of pipe or section filled with water This results in a normal maximum distance between S: cross section supports of 5.5 m.

Pmax: maximum service pressure for anchored joint Pipes should be fixed to the supports with mild steel γ: soil/pipe friction coefficient straps, so that axial movement due to expansion or Φ: angle of internal friction. contraction resulting from temperature fluctuation is G: block weight taken up at individual joints in the pipeline. In addition, γ: bulk density of concrete (22 000 N/m3) joints should be assembled with the spigot end D: pipe diameter withdrawn 5 to 10 mm from the bottom of the socket to accommodate these thermal movements. Pipes supported in this way are capable of free deflection and axial movement at the joints which accommodate small movements of the pipe supports. Purpose designed anchorage must be provided to resist the thrust developed by the internal pressure bends, tees, etc. When determining the actual position of the support centers, it should be borne in mind that the length of pipes is subjected to manufacturing tolerances.

Hypotheses o R passes through the central third of the block base. o The hydraulic thrust on the top bend is not taken into account

Block dimensions L = [6Fcosα/γβ](1/2) H = 0.5 L tg a+ a (a = 0.10 m mini) G = γLBH Where: F = W (sin a - fcos ?) Φ f = a2 tg (0.8. ) with a2 = 1 pipe coated with zinc+varnish 2 a2 = /3 pipe in PE sleeve, PE or PU For Unsupported spans slightly larger than the Other conditions to be checked: normal 5.5 m o anchored joint resistance: W < Pmax . S If necessary, unsupported spans between 5.5 m and 6 m o block non-slippage: Fcosα / G ≤ 0.9 tg Φ can be obtained by positioning the pipe supports relative (otherwise increase H) to the pipe joints as indicated in the following figure.

HIM PRABHAT 52 AUGUST 2019 TUNNELS

The following recommendations are for standard 4 m long pipes and take account of above factors. Standard 4 m long flanged pipes with welded-on flanges installed as a continuous beam. The recommended maximum unsupported span is 12 m preferably with the supports located at the center of every third pipe.

For Unsupported spans between 6 and 11 m Where a support cannot be provided at every pipe, e.g. at stream crossings etc., unsupported spans of up to 11 m can be installed by positioning supports relative to joints as indicated in following figure. The length of dimension A should not exceed one quarter of the total span length. Cut pieces, fittings, valves, etc., which are adjacent to the span, must be positioned outside the joints marked X and the length between the joints X-X must be equal to 3 full length pipes, i.e. 16.5 m. Standard 4 m long flanged pipes with screwed-on flanges installed as a continuous beam. The recommended maximum unsupported span is 8 m. The supports must be located at the center of every second pipe as shown in the following figure.

Flanged Pipes Flanged pipes are subjected to stress caused by internal pressure and stress due to local bending moments created by tightening of the bolts. Flanged pipes installed as self-supporting spans are subjected to additional stress due to bending Standard 4 m long flanged pipes with welded-on moments caused by their own weight and the weight flanges installed as a beam with fixed ends (stream of their contents. crossings). The length of unsupported spans of flanged piping The recommended maximum unsupported span at are limited by the need to confine stress due to the stream crossings, etc. is 12 m. The relative positions of combined effects of internal pressure, bolt tightening and pipe joints and pipe supports should be as shown in the bending moments, within safe limits. figure below.

AUGUST 2019 53 HIM PRABHAT TUNNELS

The supports of all flanged pipework spans must be GUIDELINES FOR JOINTING OF DUCTILE accurately align to ensure each support carries its share of IRON PIPES: the weight of the pipeline and they must be stable and unyielding since movements of the supports will induce additional bending moments in the pipeline. The straps must prevent any lateral movement or lifting of the main but not restrict expansions and contractions of the main caused by temperature fluctuations.

PIPELINE IN TRENCH: Consideration of Laying Depth: o Nature of surface load - a) Vehicular traffic load. b) Non-vehicular load. o Depth of underground facilities like telephone cables, sewers etc. o Nature of soil - a) Soft / hard / rock. b) Presence of underground water. Generally, unless otherwise specified, the normal trench depth is such that the depth of backfill above the crown of the pipe is not more than 1m.

Width of Trench: Unless otherwise specified, the width of trench is outer diameter + 600 mm.

Trench Bottom & Pipe Bed: The trench bottom provides the pipe formation. In case Permissible deflection in each joint: of homogenous soil, it can be laid directly on soil. The trench bottom must be leveled to comply with the longitudinal profile of the main and all stony protrusions on rubble must be eliminated. In case of very hard soil / rock, a sand bedding of minimum thickness of 10 cm should be provided.

PIPELINE IN SOFT GROUND: Sometimes, the layout of pipeline forces pipe to be laid in soft ground. Ductile Iron pipeline if installed in soft ground will be able to adapt to ground movement. If the settlement is uneven to some extent, Ductile Iron pipe can adapt the same due to flexibility of joints. For example a DN1000 pipe with length of 5.5 m and allowable deflection angle of 1.50, can permit a deflection up to 190 mm. Underground DI pipelines do not require to be supported at the location of joints.

HIM PRABHAT 54 AUGUST 2019 TUNNELS

ELECTROLOCK RESTRAINED JOINT : Basic Features: In a working pipeline thrust forces develop at change of o Can withstand very high pressure. direction which may lead to joint separation. Restrained o Two socket chambers - one for sealing and the other joint pipe and fittings are used in pressurized Ductile for restraining axial movement. Iron pipelines to prevent separation of the joints due to o The water sealing is done by push-on gasket and thrust forces. For more demanding restraining restraining is done by a weld bead and locking bar. requirements and particularly at difficult terrains o Normal push-on joint gasket to be used for sealing. Electrosteel offers the Electrolock self-restrained joint. o After assembly, the locking bars in parts are to be This double chamber socket joint uses the same gasket as inserted in the locking chamber. The weld bead on the traditional joint with a second chamber providing the spigot gets locked with the locking bar against anchorage provided by specially designed locking rings separation force. which locks with a weld bead made on the jointing o Can be used for trenchless applications where all spigot. Electrolock joints are already extensively used in pipes with such joints are used in the trenchless various projects. Electrolock pipes are supplied with portion. compatible Electrolock Fittings. o Easy to assemble and disassemble when required.

AUGUST 2019 55 HIM PRABHAT TUNNELS

ELECTROLOCK RESTRAINED JOINT: Disassembly of Spigot End with Welding Bead: INSTALLATION GUIDELINE: Push the spigot end of the pipe up to the stop in The installation recommendations are valid for pipes and the socket. fittings made of ductile cast iron with ELECTROLOCK o Remove the rubber blocks (EPDM rubber piece). restrained joint system made as per ISO 2531 / EN 545. o Remove the metal locks through openings provided for this purpose.

ELECTROLOCK FITTINGS:

HIM PRABHAT 56 AUGUST 2019 TUNNELS

GALLERY: Use of DI pipes in Tunnel

AUGUST 2019 57 HIM PRABHAT BRIDGE ANJI BRIDGE — ADOPTION OF CABLE STAYED BRIDGE

1 USBRL PROJECT: BRIEF HISTORY SH. B.K. SHARMA 272 km of Udhampur-Srinagar-Baramulla Rail Link (USBRL) Project is being Dy. CE constructed by Indian Railways as National Project in the State of Jammu & Anji/USBRL Kashmir. The Railway Board, Government of India entrusted the construction of Udhampur-Katra section of USBRL Project to Northern Railway which already stands completed and is under operation. The construction of rest of the section viz. Katra-Baramulla has been entrusted to Konkan Railway Corporation Limited (KRCL) and IRCON. The construction from Banihal to Barramulla has also been completed and is already commissioned. The construction activities from Katra-Banihal section of the Project are under progress and are under different stages of completion. 1.1 Importance of Bridge Since ancient times, bridges have been the most visible testimony to the contribution of bridge. Bridges have always figured prominently in human history. Some bridges embody the spirit and characteristics of a people or a place as: The Brooklyn Bridge for New York City, the Golden Gate Bridge for San Francisco, the Tower Bridge for London, the Harbor Bridge for Sydney and the Howrah Bridge for Kolkata. Similarly, Chenab and Anji Bridges always figure prominently in the Udhampur-Srinagar- Baramulla Rail Link (USBRL) Project. 1.1.1 Location of Anji Bridge Anji Bridge is proposed to be constructed between Tunnel T-2 (towards Katra side) and Tunnel T-3 (towards Reasi side) across Anji Khad (tributary of River Chenab). Construction of Anji Bridge is extremely challenging Engineering task in the balance work of project traversing through young Himalaya. Although, it is smaller in comparison to Chenab Bridge but it is also an important bridge on this section and after construction, it will be 195m above the river bed and main span across steep slope of Anji Khad River will be more than 290 mtrs.

2 ANJI BRIDGE: BRIEF HISTORY Work for construction of Steel of main Arch Span of 265m with approach viaducts on either side was awarded to M/s. Gammon India Limited- Archirdon Construction (Overseas) Co. S.A. (JV) in the year 2004 by KRCL. Lump sum contract for piers and structure as a design & built contract was awarded on 15-09-2004, with original D.O.C up to 14-03-2007, further extended

HIM PRABHAT 58 AUGUST 2019 BRIDGE

upto 30-09-2009. Construction of the Bridge was in engagement of a Group Expert/Specialised progress but due to some problems being faced by Consultants to advise and assist all-Rlys., executing agencies in construction due to difficult KRCL and the contractual agencies geology, Railway Board constituted a Committee to engaged- on technical matters as they arise review the alignment and the work was pended by on a continuous basis. This group should Railway Board vide its letter No 86/W2/NL/NR/25 Pt deal with not only with Chenab Br but also III dated 14.7.2008. the one across Anji Khad and any other Status of Old Contract for Construction of Bridge: structure which the Rly. feels it is necessary Work was pended on 25-07-2008 and contract to seek assistance, such as Br 39. The need foreclosed on 09-08-2010 due to prolonged to adopt measures to stabilise slopes below pendency (due to review of alignment). At the time the foundation levels can be got examined of foreclosure of work, concreting of foundation of by this group, a point made by Prof. Golsier Pier P-14, P-15, P-16, P-18, P-19 & P-20 were and considerably emphasized by him. completed. v Such aspects as instrumentation of the bridge, inspection and maintenance 3 COMMITTEE TO REVIEW THE ALIGNMENT procedure, equipment, plant & machinery An Expert Committee to review the alignment of the required, organizational structure that needs project was formed headed by Sh. M. Ravindra. The to be put together and retention of the Expert Committee in its report in June, 2009 cable car for future use, have already recommended the following for Anji Bridge. engaged the attention of the Railway. These 3.1 Para-7.1.5 of the Report: Common are very important issues. The committee recommendations for Chenab & Anji Bridge: recommendation achieving a finally on i A UDEC / 3DEC analysis be done for these in time. further confirmation of the stability of 3.2 Para-7.1.6 of the Report: Recommendation slopes. The analysis can be 2D, proceeding for Anji Bridge over & above Chenab Bridge: further to 3D later, if necessary. It is i Conducting a bore-hole test on either side understood that IIT/DLI can assist in this of the Khad using a triple core tube with assignment. split type sampler would be necessary. ii Based on the deliberation the sub- ii The installation of cable car on the Katra committee had at Bangalore, and for the end for assembly of the arch will entail numerical calculation with a dis-continuum large excavation measuring more than model, required tests are to be performed to 800000 cum. Such flattening will have an generate in put parameters for such influence on the stability of slopes on the calculations. Paragraph 3.6.1 can be Katra end. This factor has not been taken connected in this regard. Further, while into account by Prof. Sitharam while doing deciding on the test to be performed, as to the stability analysis; this feature may be whether any test needs to be repeated in taken into account. view of the unreliability of some of the test iii A doubt has been raised about the presence conducted earlier needs to be examined. of a shear zone below the foundation of the iii The work of Prof. Sitharam is yet to be viaduct on the Reasi end. This needs to be cleared by the Proof Consultant in writing, verified in the field. though verbally the answer is in the iv There is one important issue relating to the affirmative. It is considered necessary to present site which has a bearing on have a written clearance of the Proof commencing work again on the project. As Consultant. mentioned earlier, the committee has not iv The committee recommends the been able to conclude that the present site is

AUGUST 2019 59 HIM PRABHAT BRIDGE

stable; it cannot be said with certainty that were used as input parameter in various the final exercise would be positive. And till slope stability analysis including the such time this is concluded, it would not be recent slope stability analysis done by possible to commence work up to Km 42. M/s. ITASCA. Any shifting of the site of the bridge iii. Prof. Sitha Ram in its report submitted in donstream as proposed by Amberg or April, 2009 has made it clear that wedge upstream as stipulated in the Railway failure is not possible at both the locations Board's directives Km 42. It is a matter for of Abutments. consideration as to whether the present site iv. International expert on slope stability be given up and the bridge shifted to new M/s. TASCA has been engaged for Bridge location either upstream or downstream for no 43, Anji & Chenab Bridge. Interim purposes of speeding up the work. The report by M/s. ITASCA has confirmed Ministry may take a view. Global stability of slopes on both ends of 3.3 Railway Board Order Anji Bridge. On receipt of Expert Committee Report, v. Additional Geotechnical investigations Railway Board vide its letter no 86/W- for Br. No. 35 (Anji old) were conducted 2/NL/NR/25-Pt IV Com dated 31.08.2009 by RITES from March, 2015 to Aug, directed NR to recommence the work on 2015 and RITES submitted its report in present alignment with following instructions on Nov, 2015. Anji Bridge:- “To carryout and submit to the Bd, as 4. TENDER FOR BALANCE WORK BY KRCL: recommended by the committee, results of tests Northern Railway vide its letter dated 20.4.2010 and studies over Bridge Anji, so as to take apprised the Board about slope stability analysis of decision on recommencing the work at Anji Anji Khad done by IIT-Delhi and requested the Bridge, between km 30-42”. Board to allow NR to proceed with the work between 1.1.1 Compliance of Railway Board instructions: km 30 and km 42 including Anji Khad Bridge. i Slope Stability analysis by SLIDE, UDEC Board vide its letter no 2010/W-2/NL/NR/10 dated & 3DEC was performed by IIT Delhi in 23.04.2010 allowed Northern Railway to proceed January’10, April’10 and September’10 with the works between km 30-42 including Anji respectively. All the reports concluded that Khad Bridge. Tender for balance work of design and slopes are stable under different loading construction of Anji Khad Bridge was invited by conditions. Further M/s ITASCA, USA KRCL and was scheduled for opening on (Slope stability expert) has been engaged for 30.03.2012, which was postponed four times till slope stability analysis of Anji Bridge Nov’2012 due various reasons. (including T2/P2 portal), Bridge no. 43 & 4.1 In the meantime, the then CAO/USBRL Chenab Bridge. approached Railway Board for shifting of ii Following tests were prescribed to be alignment of Anji Bridge on the upstream side. conducted during meeting: Decision conveyed by Railway Board through a. In situ shear test in drift on both sides. its letter dated 15.11.12 is enumerated verbatim b. Plate load test in drift on both sides. as follows: c. Seismic shear wave velocity Test. “After careful consideration of the matter, Board d. P&S wave velocity test. (ME) has agreed to Railway’s proposal contained e. Bore hole, one on either side using triple in their letters under reference for shifting of core tube with split spoon sample. location of Anji Bridge on the upstream side and Note: Tests mentioned at S. No. i, ii & v the resultant modification in the alignment. have been conducted and there results Board (ME) has also desired that Railway may

HIM PRABHAT 60 AUGUST 2019 BRIDGE

carry out detailed Engineering including simultaneously. Accordingly present CAO/ geotechnical studies and mark the actual USBRL took a well-informed and concise alignment at site, work out the revised cost decision to retain the old location of Anji Bridge including the cost of abandonment of the works so that project is not delayed. done and proceed further." 5.2 Detailed Design and Construction super- In view of Railway Board letter dated 15.11.2012, vision (DDC) Tender for Anji Bridge: the NIT was finally withdrawn. Although, approved General Arrangement Drawing (GAD) was available for execution but 5. PROPOSALS TO RAILWAY BOARD (ME) FOR the same required review to check the PERMISSION TO GO AHEAD WITH applicability of the scheme involving heavy CONSTRUCTION OF T2 AND ANJI BRIDGE cutting of steep slope on Katra side to AT OLD LOCATION: accommodate cable crane for Launching of Arch As per railway Board directions ( Para: 3.3 above), of the Bridge and simultaneous construction of tests and studies required for firming up decision for Tunnel T-2. recommencing the work at Anji Bridge between Km 5.3 Necessity for appointment of DDC: The 30-42 were carried out. Analytical studies for slope Surface Geology studies of the area revealed that stability of Anji Bridge at old location by the steep slope comprised dolomite and Cherity International Expert on slope stability M/s. ITASCA dolomite, highly weathered, highly fractured confirmed global stability of slopes on both sides and with intercepts of shear seams in between additional investigation conducted by M/s. RITES bedding planes. Previous schemes of also did not showed any adversity, therefore construction of tunnel was planned with an adit CAO/USBRL on 02.12.2013 submitted a proposal (which means to have an alternate access for to Railway Board (ME) for permission to go ahead tunnel execution) of approximately 100 m to be with construction of T2 and Anji Bridge at old constructed to avoid interference with the location Committee to review the alignment with adjoining bridge work and allows to start the detailed multi-criteria analysis of various variables. work without waiting for completion of CAO/USBRL again on 22.4.16 apprised Railway bridge. Work of adit was started and executed Board regarding delay of works of Anji Bridge. for about 50 m but the ground collapsed and Board through its letter dated 28.04.2016 the portal washed away with slope debris. directed CAO/USBRL to take necessary action to Tunnel System which includes the main tunnel resolve issues. with a Parallel Escape Tunnel has to planned 5.1 Decision to retain construction of T2 and taking into consideration, Safety and Anji Bridge at old location: The location of Economical aspect so that most suitable solution the Bridge is bound by two tunnels on either is adopted. side (Tunnel T-3 on Reasi side and Tunnel T-2 on Katra side). Work of Tunnel T-2 was also Keeping in view all the above aspect it was pended due to pending decision on review of decided to appoint a Detailed Design alignment. On Reasi side, sufficient space is Consultancy (DDC) by inviting Global available for construction activities but on Katra tender so that the scheme of Bridge side, the working space is very limited which is Construction can be modified to improve the further constraint due to tunnel portal of Tunnel construction scheme of the existing GAD or T-2 (T2P2). suggest alternate solution based on designers experience, capability and vision. Designer Keeping in view the schedule of completion of was advised to suggest atleast two alternate project, the work of Tunnel & Bridge solutions in addition to existing scheme of construction is required to be executed Arch Bridge.

AUGUST 2019 61 HIM PRABHAT BRIDGE

6. APPOINTMENT OF DETAILED DESIGN AND both sides of the Anji valley; CONSTRUCTION SUPERVISION ( DDC): ii Any cut in these layers can cause land slide, After reviewing the progress of work vis a vis the as the service road built on Katra side available workload amongst both PSU (KRCL & shows; IRCON), it was decided to transfer work of iii The deep slope on the left (Katra) side is construction of Anji Bridge and adjoining tunnel to very inclined from the bottom up to the M/s. IRCON. After inviting the global tender M/s. end of the future tunnel, while on the right IRCON awarded the work of Detailed Design and (Reasi) side, there is a flat area, about 350 Construction supervision ( DDC ) to M/s. ITAFERR m long, between the slope of the river and S.P.A Italy on 26.04.2016. the beginning of the already built tunnel.

6.1 Site visit by DDC: As consequence of these points it is compulsory to investigate Prior to attempting the detailed design of the feasibility of solutions avoiding any cut on the slope of bridge, the designers must visualize and form a Katra side mental image of the bridge at the proposed site Keeping these aspects in consideration, DDC with a detailed fitment of all the components. A commented on the old existing scheme (Arch Bridge) possible configuration may appear as a flash of and suggested two alternate solutions: both asymmetric inspiration on rare occasion. But normally the and without any substructure on the Katra side, but a configuration evolves slowly as the designer small abutment placed in a favourable area. mentally examines the imagined structure with 6.2.1 Shortcomings of the Old Scheme (Arch - regard to various requirements. Accordingly the Bridge): Consultants of M/s. ITAFERR S.P.A Italy i The arch foundation on Katra side needs visited the site of the proposed Bridge on deep cuts in the unstable slope. As a 12.05.16 to 13.05.16 and also presented a brief consequence: about the possible solution for construction of a. Extensive additional surveys and Bridge at CAO/USBRL office Jammu on controls, lasting a number of months, are 14.05.16. Consultants of M/s. ITAFERR S.P.A necessary. Italy again visited the site of the proposed Bridge b. Important preliminary works to stabilize on 12.05.16 to 13.05.16. the cuts are necessary. Cost apart, they 6.2 Detailed Presentation by DDC: too need time. All the available reports on geological investigation carried out from time to time at this site along with other studies carried out in connection with construction of Anji Bridge were supplied to DDC M/s. ITAFERR S.P.A Italy. After study of the available reports and information gathered on site visits, Consultants of M/s. ITAFERR S.P.A made a detailed presentation of 21.06.2016 in corporate office of M/s. IRCON.

During presentation, the main aspects for ii A heavy equipment (“Blondin”) spanning deciding the type of Bridge to be adopted for about 300 m and able to carry at least 30 this site are listed as follow: tons is necessary to build the arch. The left i The first layers of the rock are highly tower of this Blondin is difficult to place as fractured (with many "shear zones") on well as to anchor to the soil.

HIM PRABHAT 62 AUGUST 2019 BRIDGE

iii The foundations of the arch are at different In a first stage the side span and a small part of the level. This unusual configuration can pose main span will be pushed (pulled) into the final position problems during a strong earthquake. without stays. All the joints of this part will be welded. iv The inspection of the arch and the After that the construction will go on by cantilevering, maintenance interventions during its service with 10 m long segments, and suspending the deck to life are difficult. the stays. The joints between the segments will be bolted. A massive concrete abutment on Reasi side will 6.2 Alternate Solutions: act as anchorage of the lateral stays and will resist all As defined in tender condition of DDC, the the longitudinal forces transmitted by the deck, both consultants of M/S ITAFERR presented in service (breaking forces, frictional forces) and during alternate solutions. an earthquake. 6.2.1 Alternate-I: Conceptualisation of the Cable Stayed Bridge: Merits: This solution derives from the i. On Katra side only a small foundation for the considerations of avoiding, first of all, abutment is needed. any cut on Katra side. It is therefore an ii. All the works are carried on Reasi side. asymmetric scheme with only one tower iii. No heavy equipment to build the bridge is requested. placed in a position where the iv. The construction phases are clear and well defined. disturbance to the slope is reduced. In v. Construction time is reduced and a reliable program order to limit the excavations as much as can be prepared. possible, the foundation of the tower will be based on a well. So doing, it is Demerits: possible to reach the sound strata of the Lack of experience of this type of Railway Bridge in rock without disturbing the slope. India, however important road cable-stayed bridges have been constructed and are successfully in service. 6.3.2 Alternate-II: Conceptualisation of the Two Span Truss Bridge: A possible asymmetrical solution without stays could be a large truss bridge with the main span still 290 m long and with the train running at level of the bottom chord of the truss. To balance the reactions the main span will have an orthotropic steel plate while the side span will The deck is composed by two steel trusses of constant have a concrete slab. height connected by transverse girders that support a concrete slab. This latter collaborates with the steel elements. The lower part of the tower (from the foundation up to the deck ) will be in concrete. The upper part, shaped as inverted Y, could have steel-concrete composite sections or, alternatively, could be made entirely with steel. The stays allow an easy construction by cantilevering, without any provisional support and without heavy equipment to carry the segments of the bridge in the final position.

AUGUST 2019 63 HIM PRABHAT BRIDGE

In a first stage, as proposed for the cable-stayed Demerits: bridge, the side span and part of the main span will i. The construction phases are complicated by the need be pushed (pulled) into the final position. All the joints of having temporary stays during the construction of this part will be welded. After that the construction and many bolted connections between the members will go on by cantilevering, with bolted connection. of the truss. That increase the construction time. Because of the length of the cantilever, temporary stays i. The inspection of the truss and the maintenance should be installed during the erection as well as interventions during its service life are difficult, also appropriate ballast on the side span during the final because of the height of the trusses. stages of the construction. Decision to Adopt Cable Stayed Bridge: Merits: During presentation, M/S ITAFERR showed some i. On Katra side only a small foundation for the examples of long span bridges constructed in many abutment A is needed. countries. After due deliberations with the constants of ii. All the works are carried on Reasi side. M/s Italferr S.p.A and keeping in view the typical site iii. No heavy equipment to build the bridge is conditions at the locations of Anji Bridge specially at requested. Katra end, it was felt that Cable Stayed Bridge would be iv. The construction phases are clear and the best option and accordingly CAO/USBRL informed well defined. the Railway Board on 23.06.2016 regarding the adoption v. On the basis of the previous points, a liable of Cable Stayed Bridge to fill the gap at Anji Khad of construction program can be prepared. USBRL Project.

HIM PRABHAT 64 AUGUST 2019 BRIDGE

EXECUTION OF 100T CABLE ANCHORS AT CHENAB BRIDGE SITE

GIRI PRAKASH BOLLINENI Ground anchors have been used since decades for slope stability Design Manager enhancement and landslide stabilization with considerable success in the environmental protection. Their beneficial effect on the slope stability is VENKADESAN B. attributed to the provided forces and moments counteracting destabilizing Business Unit Head forces/moments and to the improvement of the shear resistance along the slip surface by increasing the normal stresses on this surface. KANNAPPAN SUBRAMANIAN Ground anchor is composed of three parts (1) ground anchor body, Chief Operating Officer (2) anchor head, and (3) relevant accessories. Ground anchor body is again divided into two parts: free anchor length and fixed anchor length. The part of free anchor length where strand or rod is covered by sheath delivers the residual force from anchor head to the part of fixed anchor length where tendon is grouted. A part of fixed anchor length again delivers residual force to ground by friction and compression. Depending on the types, ground anchor systems requires its own relevant accessories (e.g., wedge, nut and saddle of anchor head) to facilitate the operation of the mechanism. The present paper explains the fabrication and installation of 100T capacity Pre-Stressed cable anchors for Slope stabilization in Chenab Bridge project.

Figure-1: Components of Ground Anchor System

AUGUST 2019 65 HIM PRABHAT BRIDGE

Figure-2: Strand Specifications The drilled hole will be checked and flushed with air to remove any loose materials and filled with water. The Prefabricated Anchors along with grout pipe will be lowered to the required length.

Figure-4: Stage Grouting

Figure-3: Fixed Length & Free Length

Grouting: Grouting will be done in 3 stages at different portions of anchor as explained below: 1st stage: Between HDPE Duct-1 & HDPE Duct-2 (Fixed Length of Anchor) 2nd Stage inside & Outside: In this stage grout will be injected to the grout hose pipes fixed inside & outside of the HDPE Duct. This operation will be stopped after the grout overflow from the top of the hole. Description of DCP Cable Anchor: 3rd Stage: will commence after completion of stressing The ground anchor is 100T capacity Double Corrosion at the location of top unfilled portion (RCC pad Protection cable Anchor (Confirming to BS 8081:1989) location) of anchor made up of 8 Steel Cables (Strands) of dia 15.7mm. After 2nd Stage grouting, Precast reaction pad of In Fixed length strands surrounded by 2 layers of 1.5m × 1.5m × 0.6 m will be brought to the anchor HDPE corrugated ducts acts as double corrosion location with help of crane and carefully placed around protection and annualr space filled with Grout. In Free the grouted anchor length, each strand is surrounded by greased filled sheathing and encased in HDPE corrugated duct acts a Stressing: corrosion protection. Base plate and Anchor block will be fixed on RC Reaction pad and the pad sealed from three sides using Installation of Anchors: the cement sand mortar and grout is poured from top Drilling through Rock will be carried out by using (under gravity) in order to fill the opening left in the pneumatic percussion method. Prior to installation of reaction pad. anchors drilling, grouting and re-drilling of hole will be Stressing operations shall be carried out after 14 days done to satisfy the permeability of the hole, ie. less than of grouting of anchors and the Grout strength attains 3 lugeons. The depth of hole will be 40 m long and dia. its strength of 30 MPa after ensuring the Design Strength of 160 mm. The borehole will be drilled by an extra based on Grout Cube Strength results. The stressing 200-300mm to ensure complete grouting at the end of shall be carried out by using multi strand jack in one the cable anchor. single operation.

HIM PRABHAT 66 AUGUST 2019 BRIDGE

Figure-5: Jack arrangements for Stressing o Test performed on first three working anchors. o Loading applied incrementally, in 3 cycles, to 150% of working load and locked at 110% of working load.

On-Site Acceptability Test: This test carried out to demonstrate the short term ability of the anchorage to support a load that is greater than the design working load and the efficiency of load transmission to the fixed anchor zone.

Figure-7: Proving Test Results

Testing of Anchors: Before any anchorage installation, it should have been proved by previous testing or by adequate properly documented site experience. The test shall be performed by incrementally loading the ground anchor in accordance with the schedule provided by BS 8081:1989. o Test performed on all working anchors. Figure-6: Proving Test Anchor Location o Loading applied incrementally to 150% of working load and locked at 110% of working load.

Conclusion: Upon successful completion of testing, cables locked at 110% of working load and Galvanized Steel Cap will be mounted on bearing plate by means of sealing and galvanized bolts and filled with corrosion protection compound (Grease) which will help for future restressing. Proving Tests: The stability of a slope is dependent on maintaining Proving tests required to demonstrate or investigate in the tension levels in the cables. Therefore, Long-term advance of the installation of a working anchorages, the monitoring of anchors shall provide the safety of the quality and adequacy of the design in relation to ground anchor reinforced slope by timely application of tendon conditions and materials used and the levels of safety that re-tensioning processes which will enable further increase the design provides. of the design life of anchors. o Proving tests conducted on 6 sacrificial Anchors of fixed lengths 6m,10m & 14m. Figure-8: Completion details of Anchor head o Loading applied incrementally, in 8 cycles, to 80% of fpu (fpu-Characteristic strength of Tendon)

On-Site suitability Test: This test carried out on anchorages constructed under identical conditions as the working anchorages and loaded in the same way to the same level to judge the performance of the working anchors.

AUGUST 2019 67 HIM PRABHAT BRIDGE

References: 1. BS 8081:1989, “Code of Practice for Ground Anchorages”. 2. IS:10270-1982, “Guidelines for Design and Construction of Prestressed Rock Anchors”. 3. IS:6066-1994, “Pressure grouting of rock foundations in river valley projects - Recommendation”. 4. EN 10138-3, “Prestressing steels - Part 3: Strand”. 5. IS 5529-2 (2006), “In-situ Permeability Tests, Part 2 : Tests in Bedrock”.

HIM PRABHAT 68 AUGUST 2019 BRIDGE

GEOLOGICAL STUDIES OF MAJOR BRIDGES AT SANGALDAN — BRIDGE 85 AND BRIDGE 87

"The foundation of bridge piers and abutments require a serious geological investigation"

SUMMARY: The new railway line project between Jammu, Srinagar and Baramulla is one of the most auspicious & prestigious railway projects after independence, aiming to connect the Kashmir valley with Jammu. The two major bridges Br.85 Br.87 are currently under construction phase at Sangaldan .The construction work remains challenge during execution due JAVEED HUSSAIN to weak geological strata having predominance of clay and fragile slopes of ALAMGEER overburden, weakfaulted and weathered Murree formation of Rocks. Senior Asstt. Geologist Stabilizing the slopes during earth cutting for Abutments and Piers posed KRCL /Sangaldan big challenge for engineers and Geologists. Planed berm cuttings in overburden / weak Murree rocks with immediate protection measures paved way for smooth functioning of the construction work. Detailed geotechnical investigation was done prior to construction work. Borehole drilling at every Abutment and Pier location was done and detailed Bore logs was prepared to give fair idea about rock types, permeability etc .Accordingly standard penetration tests (SPT) inside drill holes at every 1.50m interval was done to see the standard penetration resistance or N-Value of soil for geotechnical design purposes and Pressure meter tests (PMT) inside drill holes at every 3.00m interval was done, the objective of the test is to determine the in-situ deformation modulus of the overburden soil/rock at respective depths in the drill hole through loading of the surrounding soil /rock up to a peak pressure of 70 or 80 bars. The Bridge No.85 will connect the Tunnel T42/43 with Tunnel T44/T45, the Bridge No.87 will connect the Tunnel T44/45 with Tunnel T46 .The Bridges No 85 is 290.49 meters in length and consists of two numbers of Abutments with four numbers of piers in-between .The Bridges No 87 is 243.45 meters in length and consist of two numbers of Abutments with three numbers of piers in-between. The construction methodology adopted in above mentioned bridges was open foundation. The paper describes the geological studies of major bridges at Sangaldan in reliance to encountered geological conditions based on Geological logs of

AUGUST 2019 69 HIM PRABHAT BRIDGE

Drill Holes along the bridge alignment and geological pit Net safe Bearing pressure based on rock classification: maps prepared after open cutting. Concise overview of Plate load tests PLT conducted at every Abutment & Pier location was conducted to ascertain the settlement in footing .The average settlement of plate will be worked out by using the formula St = Sp [B (Bp+0.3) / Bp (B+0.3]² Where B: size of footing in m, Bp: size of test plate in m, Sp: settlement of test plate in m, St: settlement of footing in m. In general IS Code 1888-1982 will be used for conducting the above tests.

Based on presumptive values of safe bearing capacity as per clause 5.2 of IS 12070-1987.

Based on RMR value: Clause 5.3 of IS 12070 - 1987. Net SBP Based on RMR

According to various codes of practices in case of filling soil material, compactness and general geology of overburden. the terrain. Indian Railway Standard Code of practice for the design of sub-structures and foundations of bridges Keywords: (Revised 1985): Geological logs, Geological investigation, Foundation, Gravel sand and gravel, compact and offering high Slope Stability, Hilly terrain, Slope protection, Rock resistance to penetration when excavating by ordinary mass, Bridge, Abutment, Pier, PMT, SPT, PLT. tools - 44.87 t / m2. Loose gravel or sand gravel mixture, loose coarse to Introduction medium sand, dry - 24.98 t / m2. At Sangaldan a series of tunnels, between the T40/41 to German specifications for foundations FRG. DIN T47 had already been completed in 2014. Because of the 1054: -Cobbles and gravels in sandy soil matrix -25 to excavation difficulties related to landslides, slope 28 t/ m2. instability and very poor rock-mass conditions, the open British specifications for foundations (CECP No. 4): - foundation methodology remains the great challenge for Cobbles and gravels in sandy soil matrix - engineers and Geologists. The deep earth /rock cutting Compact - 40 to 60t/m2 required for pier and abutment foundation was Less Compact - 20 to 40t/m2 successfully tackled with proper slope cutting with berms Above recommended values have a wide range and the and adequate slope protection measures was put in choice of design value should be based on the nature of practice to avoid any slope failures.

HIM PRABHAT 70 AUGUST 2019 BRIDGE

The geological strata encountered during execution of GEOLOGICAL OVERVIEW OF THE AREA major Bridges at Sangaldan belonging to the Murree formation (sandstone, siltstone, claystone) .The Murree Regional Geology Formation has been named after a village in Pakistan. The Kashmir railway link ,heading northward from katra The Murree Formation is predominantly composed of crosses up to Banihal ,a main part of the Indian margin sandstone, Siltstone, Claystone and shales with ripple of the Himalayan collisional range ,by now concordantly marks and pseudo-conglomeratic structure. This constituted by three major units ,the sub-himalaya and Formation forms the inner part of the foreland thrust the lesser and the higher Himalaya crystalline, belt (Tertiary belt of Jammu & Kashmir) extending respectively divided ,in this chain sector ,by the Murree from Pooch to Basoli and laterally up to Pakistan in the thrust and the panjal thrust. west. The Murree Formation has been divided into These main thrusts as well as most of the belts and Lower and Upper Murree formations, which are in units of this NW region of Himalaya orogeny show a conformable contact. regional strike of NW-SE to WNW - ESE with moderate The sediments of the Murree Group form a broad to steep dips either towards north or the south. rim in the inner Tertiary belt of the Himalaya, extending Within this regional geological context, the major bridges from the Jhelum syntaxis to the Jammu foothills on the at Sangaldan mainly crosses the rocks belonging to Indian subcontinent. The Murree foreland basin, in Murree formation,The entire area consists of Murree which the sediments from the Himalayan uplifts have formation of rocks of Upper Eocene age the area is accumulated, was formed as a result of the early Tertiary rugged and occupied by high hills with deep depressions Himalayan Orogeny. Recent paleo magnetic and and Nalla in between. Generally hill slopes are covered paleontological studies have revealed that these sediments with a layer of slope debris derived from parent Murree were deposited in the late Eocene-early Miocene. rocks consisting of clay shale /clay stone, siltstone& Lithologically, the Murree Group of rocks has been sandstone trending NW - SE. divided into a Lower Murree Formation, exhibiting a cyclic sandstone-siltstone-mudstone sequence, and an The generalized geological succession in the region is Upper Murree Formation with sandstone-mudstone given below: cycles. The individual cycles in the Lower Murree start with an erosional base, followed by channel-lag conglomerates, cross-bedded sandstones with thin mud flasers and massive sandstones. The latter are overlain by laminated sandstones displaying ripples, massive sandstones and mudstone-siltstone intercalations. In the upper Murree Formation, the arrangement of the rock units changes with a general increase of sandstone facies as compared to mudstone facies. The absence of siltstone facies is a characteristic feature in the Upper Murree Formation. The presence of strongly bioturbated, pebbly & cross-bedded sandstones with thin mud flasers indicates deposition in a subtidal environment. The sandstone -mudstone intercalations along with laminated siltstones represent a mixed tidal flat sequence deposited in the intertidal zone. Slope instability phenomena are widely presents along the length of bridge alignment, both as slow but wide and deep landslides and as shallower but faster debris flows / rock falls.

AUGUST 2019 71 HIM PRABHAT BRIDGE

Considering the available data coming from the oriented (i.e. the direction of maximum horizontal world stress Map - WSM (a global compilation of compressive stress-sh max - is almost parallel to the information on the present day stress field of the earth's direction of plate motion).At regional scale under- crust with 21.750 stress data records in its current WSM thrusting of the Indian plate below the Eurasian database release 2008 ,http://dc-app3-14.gfzpotsdam.de/ plate thrust faults are propagating to the foreland side of pub/introduction/introduction_frame.html,the project the Himalaya indicating southern most front as a most zone falls very near the border between the Asian and the active zone. Indian plate. This is also shown by focal mechanism solution of a The available stress indicators are earthquake moderate to large earthquakes that are mainly thrust type focal mechanisms, most of them indicating a events .However ,there are some events along the compressive field with principal tensor NNE-SSW transverse fault indicating strike slip motion.

HIM PRABHAT 72 AUGUST 2019 BRIDGE

Local Project Geology In actual fact, these rock types represent the complex The rock exposed in project area belongs to lower succession of continental sediments, ranging from clay to Murree formation which is represented by alternate sand showing different depositional energy degrees. sequence of siltstone, sandstone and claystone bands .Bed rock exposures are seen in nearby area of the proposed Geological Considerations for Bridge Construction: bridge sites along the approach road cuttings, Nalla A bridge may be defined as a structure built over a river, cuttings and ridges. The rock type exposed in area is a dry valley, low land or an estuary or any depressed part purple brown to grayish brown alternate bands of of the land to provide a link between the two opposite Sandstone, Siltstone and Clay-stone. Rocks are soft to sides. It is essentially a communication link on a road or hard, massive, closely jointed, shattered and sheared. A railway track or a highway. Bridges especially over major major Discontinuity known as Murree Thrust crosses the rivers and in hilly and mountainous areas are very alignment somewhere near Dharam village. Murree important civil engineering structures. Their role in thrust separates the younger Murree rocks from the socio-economic development and defense strategies can overlying older Dogra Slates of Precambrian which is well hardly be overemphasized. known in the geological literature. Another Saladar In most cases the location of a bridge is decided more thrusts present within Ramban slates has merged with by socio-economic factors than by geological Murree thrust in this area. Due to the presence of considerations. Thus, there are two major bridges in Saladar& Murree thrusts, rocks in the area especially USBRL project at Sangaldan connecting tunnels Murree group of rocks is badly damaged & crushed. T42/43 with T44/45 and Tunnels T44/45 with T46.

AUGUST 2019 73 HIM PRABHAT BRIDGE

Within big cities divided by rivers or streams, a bridge up to a reasonable depth. Utmost care is needed not has to be placed where it is needed, irrespective of the to mistake isolated big boulders buried underneath subsurface geology. the river bed as the bed rock. However, on highways, there is often some flexibility o Boulders are rocks but they are not bed rocks and available in the choice of placement of a bridge. This is cannot be trusted as foundations for bridge piers. unlike tunnels and bridges, where alignment is primarily and essentially controlled by geological considerations. (b) Nature of Bed Rock: The very first rock But, in the case of bridges also, the design, stability and encountered below the bed cover material may not be durability depend, to a great extent, on the subsurface suitable as a foundation. geological conditions that must be properly investigated It should be kept in mind that three types of loads are to and cautiously interpreted. In any major bridge be borne by a bridge pier foundation: construction project, the designer is keen to place the i. The compressive, vertical loads due to the weight of bridge abutments and piers on as sound, strong and the bridge span and that of pier material; stable rock foundation below as possible. This being so, ii. The horizontal loads due to the thrust of the water the geological characters that need to investigate and flowing above as transmitted directly and through thoroughly established are: the pier; (a) The depth to the bed rock; iii. The dynamic, complex load, often inclined and (b) The nature of the bed rock; shearing in character, due to heavy traffic on the (c) The structural disposition of rocks. bridge. Consequently, the bed rock selected as foundation for (a) Depth to Bed Rock: In most cases, the river bed the pier must be strong enough to bear the sum total of below the water is covered by varying thickness of all these loads, not temporarily, but throughout the unconsolidated natural deposits of sand, gravels and proposed life of the bridge. boulders. The nature of the bed rock is commonly determined through study of petrological characters and engineering Such loose materials are not safe as foundations for properties, especially the strength values, using the core bridge piers for at least two reasons: samples obtained during drilling of test bore holes. In o Firstly, piers placed directly on them would be fact complete and very useful geological profiles could be unstable; prepared all along the centre line of the proposed bridge o Secondly, the cover material is liable to be removed from the study of such core logs. due to scouring by river water. These (profiles) would depict complete sequence (and o As such, the pier must be placed on stable even structural disposition) of the rock formations foundation, preferably of rock, under a suitable existing below the surface material up to a desired depth. thickness of cover material so that it is safe from A decision to place the pier on a particular rock at a scour by river water. particular depth is then matter of judgment and design o The height of pier from under the span to the requirements. foundation level, therefore, depends on the 'depth of Most igneous and massive type of sedimentary and the bed rock' below the river water. metamorphic rocks is quite strong, stable and durable as o Such sound bed rocks might be available within a foundations for bridge piers and abutments. The group depth varying from 5 to 20 meters below a river bed of weak rocks which might behave badly in the presence or they might not at all be available even up to 100 of water includes such types as cavernous limestone's, meter or more .All that depends on the local geology chalk, friable sandstones especially with clayey cements, which has to be investigated and understood. shales, clays, slates, schists and the layers of peat and o To achieve this, drill holes are made all along the compressible organic material. centre line of the proposed bridge, even on the right Many of them are amenable to treatment by artificial or left of it, till they reach the sound rock sequence or methods.

HIM PRABHAT 74 AUGUST 2019 BRIDGE

(c) Structural Disposition: Ideally, the horizontal The slope protection works was mainly soil slope; soil- attitude and uniformly massive structure with depth are rock slope and rock catch type. desirable characters in the foundation rocks as these offer For a soil slope, soil nailing, revetment wall or stone inherent resistance against failure. However, even masonry walls have been used to protect the slopes to inclined rocks in a confined situation under the bridge control slip /slides. For highly fractured rock mass, the piers are considered quite safe if these possess normal revetment wall, SDA, wire mesh shotcrete was applied to strength values. protect the slopes as per the site condition. In the Folding and faulting might cause some uncertainty in special protection works such as planer, wedge and establishing a perfect geological profile but are not toppling failure ,we can stitched the jointed rock otherwise negative factors. Acute fracturing and profuse mass by fully grouted rock anchoring, dowelling with or jointing is, however, undesirable at the foundation without shotcrete as per site condition but detail levels as these might cause settlement beyond the kinematic slope stability analysis have been done to check allowable limits. the failure mechanism. When the bridge sites are located in the zones of As we know this area exists in zone IV on earthquake seismic activity, the foundations are required to be zonation map of India. The topography of this area is designed for additional seismic loads as specified in the much roughed and geologically very complex in nature. codes of respective areas. Due to weathering (physical, chemical and biochemical) In the glaciated areas, special care must be taken to that drastically decreases strength parameter of rock mass. establish the existence of drowned or buried valleys that When the shear strength parameters of the rock mass might be filled by secondary material of most are reached at peak value due to natural or manmade heterogeneous characters. In such cases a bed rock may forces, slope fails in continuum or discontinuum be encountered only at great depth and it may be materials. Most of landslides /slip failures of the project desirable to reach it through piles. In fact, occurrence of area are governed by weak geological strata of Murree drowned valleys is considered one of the major formation having clay dominance. complications in bridge foundations that limit the The nature of slide is governed by kinematic options of a design engineer. mechanism and required slope protection as trimming of Similarly, the factor of scour must never the the slope, berm cutting, SDA, Shotcrete and rock overlooked. Riverbed materials and rocks under them at bolting. The shotcrete wire mesh, SDA, rock bolts shallow depths are liable to removal by scouring. The revetment wall has been used to protect slopes. scour itself is a function of river velocity and direction of Sometimes slope failure have occurred along closely the currents on the one hand and nature and degree of spaced and steeply dipping joints as a planar and wedge consolidation of the rocks on the other hand. mechanism due to the intersection of adversely-oriented joint planes. For control measure of this slip failure we Slope Protection works: have first redesign the slope face geometry and removed As the terrain of the project is through the mountainous all loose materials from rock slope then we have done region, various protections works, such as revetment rock bolting/SDA & wire mesh shotcreting. A detail walls, Shotcrete, SDA, rock bolting and special slide analysis has been carried out before finalizing special protection works have been done to stabilize the slopes. protection measures.

AUGUST 2019 75 HIM PRABHAT BRIDGE

Slope protection at Bridge No.85 (P1)

Slope protection at Bridge No.85 (P1)

HIM PRABHAT 76 AUGUST 2019 BRIDGE

Slope protection at Bridge No.85 (P3)

Slope protection at Bridge No.85 (P4)

AUGUST 2019 77 HIM PRABHAT BRIDGE

Slope protection at Bridge No.87 (A1)

Slope protection at Bridge No.87 (P1)

HIM PRABHAT 78 AUGUST 2019 BRIDGE

BRIDGE NO 85: of moderately weathered medium to fine grained, The Bridge 85 is located from chainage Km. 96/298907 moderately to highly fractured medium strong, jointed (A1) to Km.96.588267 (A2) on Dhalwa Nalla with and fractured sandstone, siltstone and claystone. minor flow except during rainy season. Thebridge consists Exposed outcrops along ridges are weathered, of two numbers of Abutments and four numbers of discolored, distorted and fragile. The bridge site is Piers.The rock exposed in project area belongs to Lower having disturbed rock mass due to the close proximity of Murree Formation which is represented by alternate Murree thrust. sequence of siltstone, sandstone and claystone bands. Bed The rockmass is traversed by two to three no. of joint rock exposures are seen in the nearby area of the proposed sets which are closed to partly open in nature. The bridge site towards down side of the hill along ridges. bedrock is dipping from 50° to 60°. The bridge site is covered by hill wash/slope debris The foundation of Abutments and Piers of bridge material consists of sub-angular to rounded fragments of No.85 was in overburden as per geological borehole data pebbles, cobblesand boulders of sandstone &siltstone which was authenticated after excavation in geological pit mixed with medium to fine grained ,reddish grey silty maps, the geological pit maps was intentionally not clay matrix. shown in report keeping more or less homogenous The rock mass in general consists of alternate bands overburden strata in consideration.

Site view of Bridge No.85 BRIDGE

Sub-surface Exploration The summary of bore holes drilled at Pier/Abutment locations is tabulated below:

HIM PRABHAT 80 AUGUST 2019 BRIDGE

Bridge No.85 Abutment A1: penetration resistance or N - value ranges from 15 to 65. The borehole drilled at chainage Km.95/985.320 reveals The geological strata encountered during geotechnical overburden material up to drilled depth of 68.00 m investigation correlates with geological pit map prepared consisting of angular to sub angular, sub rounded, after excavation. boulder, cobble, pebble size fragments of sandstone The Rock mass rating (RMR) of geological strata mixed with silty clay matrix interpreted as slide cum during geotechnical investigation at Br.85 A1 is IVPoor. slope debris material. The foundation level of the bridge was at RL 1245.35m level which was in overburden, for Bridge No.85 Abutment A2: calculating safe bearing pressure SBP ,Plate load tests The borehole drilled at Chainage Km.96/274.680 reveals PLT was done to ascertain the settlement in footing . overburden material up to drilled depth of 40.00 m Cyclic plate load test has been conducted at Bridge consisting of angular to sub angular, sub rounded, No.85 A1 Ch :96/298.9 Km .The plate test was boulder, cobble, pebble size fragments sandstone mixed conducted at a depth of 16.75 m BGL below ground with silty clay matrix interpreted as slide cum slope level at (RL 1243.85) .At this site stratum consists of debris material. slope debris /overburden material comprising of medium The bedrock encountered at 40.00m to 51.30m to fine grained ,reddish brown silt & clayey silt with depth comprises of fresh to slightly weathered, partial to pebbles ,cobbles and boulders. Slope debris is damp and moderately fractured, moderately strong, well bedded, water dripping points are noticed at few places. Initially jointed greyish sandstone interbedded with weak to at same chain age, Ist PLT was conducted between moderately strong, and reddish brown siltstone. Staining 17th& 18th Feb 2017, where SBP observed was about along the structural planes was also found. Calcite veins 25.41T/m2.As this does not meet with design are also noticed. requirements of SBC of 40T/m2.Therefore, Second PLT The geological strata encountered during geotechnical was conducted between 21st& 22nd March after investigation correlates with geological pit map prepared excavating soil of 1.5 m below first PLT location. In this after excavation. cyclic PLT, under action of 50.05 T/m2 pressure, The foundation level of the bridge was at RL estimated settlement of Abutment location is 7.299mm 1215.50m level which was in overburden, for calculating which was less than the permissible settlement of safe bearing pressure SBP, Plate load tests PLT was done 12mm.It is important to mention at this site, foundation to ascertain the settlement in footing . was resting on slope debris material which is basically Cyclic plate load test has been conducted at Bridge very stiff to hard clayey silt in nature. Hence, correction No.85 A2 Ch: 96/58 Km .The plate test was conducted for slope which is normally applied for sloping rock mass at a depth of 11 m BGL below ground level at (RL is not applicable here. From the results it can be 1249.00). summarized that PLT at Abutment A1 ,existing stratum At this site stratum mainly consists of slope wash at depth of 16.75m below ground level (RL 1243.85) is material in the form of very hard clay up to 40m. Cyclic having SBC of about 40.0 T/m2. plate load test was conducted between 03.04.17 & The bedrock encountered at 68.00m to 75.00m depth 04.04.17 In this cyclic PLT, under action of 150.14 comprises of weathered, weak, fractured, fine grained T/m2 pressure, estimated settlement of Abutment reddish grey claystone to medium strong moderately location is 17.498mm From the results it can be fractured medium to fine grained reddish grey siltstone. summarized that PLT at Abutment A2, existing stratum Staining along the structural planes was also found. at depth of 11m below ground level (RL 1249.00) is Standard Penetration test (SPT) for geotechnical having SBC is more than 50.04T/m2 which is more than design purposes was done from 0.00 m to 55.00m depth. assumed design value of 45T/m2 for bridge 85 - Mostly the refusal of SPT was seen during test due to Abutment A2. heterogeneous overburden of intermixing soil mixed with The Rock mass rating (RMR) of sandstone exposed fragments of pebbles, cobbles & boulders of siltstone along Br.85 A2 is III Fair and Rock mass rating (RMR) &sandstone. The assumed corrected Standard of siltstone exposed along Br.85 A2 is IV- Poor.

AUGUST 2019 81 HIM PRABHAT BRIDGE

The borehole drilled at chainage Km.96/033.310 greyish sandstone. Staining along the structural planes reveals overburden material up to drilled depth of 59.00 was also found. m consisting of slope debris /overburden material Standard Penetration test (SPT) for geotechnical comprising of medium to fine grained, reddishbrown, design purposes was done at every 1.50 meters from 0.00 semi-unconsolidated mixture of silt and clay with angular m to 36.00m depth. Mostly the refusal of SPT was seen to sub angular, sub rounded, boulder, cobble, pebble size during the test. Penetration was found from 2.00cm to fragments sandstone, siltstone and claystone mixed with 26.00cm in most of the test stretches while hammering fine grained reddish grey silty clay matrix. 50 blows / 30cm as per the test procedure. The Standard The bedrock was not encountered up to the penetration resistance or N - value ranges from 23 to 75. foundation depth (1232.04 m) at Ch Km 96/346.897 Pressure meter tests (PMT) was taken at every 3.00m which correlates with the borehole log of bridge 85P1 interval all through up to 36.00m depth.The test was prepared during geotechnical investigation works. done inside drill holes at every3.00m interval; the The RL of foundation PCC top at location is objective of the test is to determine the in-situ 1232.04m.Excavtion starting edge is at RL 1260.00m, deformation modulus of the overburden soil/rock at hence the maximum height from bottom of foundation respective depths in the drill hole through loading of the to the excavation starting edge is 28m.Bedrock is not surrounding soil /rock up to a peak pressure of 70 or 80 encountered to the foundation depth 1232.04m which bars. The test was used in geotechnical investigation to correlates with borehole data. know the stiffness or complete deformation due to The bedrock encountered at 59.00m to 62.00m looseness or oversize of borehole in ground. Overview of depth comprises of fresh to slightly weathered, PMT was given and the detailed discussion regarding moderately fractured medium to coarse grained strong PMT is beyond the scope of this topic.

HIM PRABHAT 82 AUGUST 2019 BRIDGE

The geological strata encountered during geotechnical to moderately strong reddish brown siltstone and investigation correlates with geological pit map prepared claystone. The rockmass is transverse by 3 sets of joints after excavation. with smooth joint surfaces in siltstone & Claystone and The Rock mass rating (RMR) of geological strata moderately rough surfaces in sandstone respectively. calculated during geotechnical investigation at Br.85 A1 Staining along the structural planes was also found. is IV - Poor. Calcite veins are also noticed. The RL of the foundation top is 1215.500m Bridge No.85 (Pier - P2) Standard Penetration test (SPT) for geotechnical The borehole drilled at chainage Km.96 /097.770 reveals design purposes was done at every 1.50 meters from 0.00 overburden material up to drilled depth of 45.00 m m to 32.00m depth. Mostly the refusal of SPT was seen consisting of angular to sub angular, sub rounded, during test. Penetration was ? 10cm in 50 blows in most boulder, cobble, pebble size fragments sandstone, siltstone of the test stretches. The Standard penetration resistance mixed with fine grained reddish silty clay matrix. or N - value ranges from 22 to 91. The bedrock encountered at 45.00m to 66.00m Pressure meter tests (PMT) was taken at every 3.00m depth comprises of slightly weathered, moderately interval all through up to 32.00m depth. The test was fractured, medium hard to soft, fine grained light grey to done inside drill holes at every3.00m interval, the reddish brown siltstone and claystone. Staining along the objective of the test is to determine the in-situ structural planes was also found. The RL of the deformation modulus of the overburden soil/rock at foundation top is 1215.500m. respective depths in the drill hole through loading of the Total 15 number of SPT taken at different depths surrounding soil /rock up to a peak pressure of 70 or 80 Standard for geotechnical design purposes from 1.00m to bars detailed discussion regarding PMT is beyond the 55.54m depth. Mostly the refusal of SPT was seen scope of this topic. during the test. Penetration was 02.00 cm to 22.00 cm The Rock mass rating (RMR) of geological strata 60 - 65 blows in most of the test stretches. The Standard calculated during geotechnical investigation at Br.85 P3 penetration resistance or N - value ranges from 20 to 82. is IV - Poor. The Pier P2 of bridge 85 is the only pier for which excavated has hampered due to massive landslide Bridge No.85 Pier P4: happened on hill side of the foundation dated February The borehole drilled at Chainage Km. 96 /226.790 2019 .This leads to delay in excavation work .Now reveals slope debris /overburden material comprising of excavation work is going on in full swing at P2 of bridge medium to fine grained ,reddish brown ,semi 85 and the excepted date for PLT test will be 25th or unconsolidated angular to sub angular, sub rounded, 26th of April 2019. boulder, cobble, pebble size fragments sandstone, The Rock mass rating (RMR) of geological strata siltstone and claystone intermixed with fine grained calculated during geotechnical investigation at Br.85 P2 ,reddish grey silty clay. Bed rock was not encountered up is IV - Poor. to the foundation depth of (1234.836) which correlates with borehole log of bridge 85P4 prepared during Bridge No.85 (Pier - P3) geotechnical investigation. Bed rock starts at RL: The borehole drilled at chainage Km.96 /162.230 reveals 1219.0m as per geological log of 85P4.The bedrock overburden material up to drilled depth of 46.25 m encountered at 25.00m to 54.00m depth comprises of consisting of angular to sub angular, sub rounded, fresh to slightly weathered, medium to coarse grained, boulder, cobble, pebble size fragments sandstone, moderately fractured, medium strong jointed siltstone and claystone mixed with silty clay matrix. grayishsandstone and siltstone.The foundation level of The bedrock encountered at 46.25m to 63.25m the bridge was at RL 1234.836m which was in depth comprises of fresh to slightly weathered, overburden, for calculating safe bearing pressure SBP, moderately to highly fractured, moderately strong well Plate load tests PLT was done to ascertain the settlement bedded jointed greyish sandstone interbedded with weak in footing.

AUGUST 2019 83 HIM PRABHAT BRIDGE

Static maintained Plate load test has been conducted at BRIDGE NO 87: Bridge -85, at the location of Pier-4, at Chainage The Bridge 87 is located from chainage Km. 98 96/540.277Km conducted at a depth of 20.2m below /344.587 (A1) to Km. 98 /587.989 (A2) on Duksar ground level (RL 1255m).At this site stratum consists of Nalla was one of the toughest bridges, keeping weak and overburden material consisting of medium to fine grained, fragile geological conditions in consideration, slope reddish to brown, semi unconsolidated mixture of silt and cuttings for open foundation in lose strata with inclined clay with pebbles, cobbles and boulders embedded in it. slopes pose major challenge for engineers and geologist Bed rock is not encountered up to the excavated depth during execution work. The proper slope stabilizing where Plate Load Test is conducted i.e.at RL 1234.8m. measures have been taken during cutting of slopes to Side walls of excavated pit are slightly damp may be evade any slip and slide failures. due to heavy rainfall before conducting Plate Load Test. The Duksar Nalla has minor flow except In this Static Maintained Plate Load test, under the considerable flow during the rainy season. The bridge action of 100.10 T/m² pressure acting on Test plate, consists of two numbers of Abutments and three Total Settlement = 5.13 mm numbers of Piers. Net Settlement = 5.12mm The rock exposed at bridge site belongs to Lower Elastic Rebound = 0.01mm Murree Formation which is represented by alternate From the graph of applied load vs. Total settlement sequence of siltstone, sandstone and claystone bands. Bed drawn on log scale, Yield stress is not observed. rock exposures are seen in the nearby area of the Hence, considering maximum pressure as ultimate proposed bridge site along the approach road cutting, pressure which is 100.10T/m² and Adopting FOS as3, Nalla cuttings and ridges. hence Allowable Safe Bearing Capacity of strata is about The bridge site is covered with 3.50m to 23.00 m 100.10/3 ˜33.34T/m² thick hill wash/slope debris material. The rock mass is Hence, it can be summarized that at the Plate Load jointed and fractured with slide area having slickenside Test location, existing stratum at a depth of 20.2m below surfaces. The trend of the rock mass is N80°W -S80°E ground level (RL-1234.8m) is having Safe Bearing dip 55°-65° northerly. The bridge site is having disturbed Capacity of about 33T/m². rock mass due to the close proximity of Murree thrust. The Rock mass rating (RMR) of geological strata The rock mass is traversed by two to three no. of joint calculated during geotechnical investigation at Br.85 P4 sets which are closed to partly open in nature. The is IV - Poor. bedrock is dipping from 55° to 65°.

The various joint sets recorded in the area are tabulated below:

HIM PRABHAT 84 AUGUST 2019 BRIDGE

Sub-surface Exploration The summary of bore holes drilled at Pier/Abutment locations is tabulated below:

AUGUST 2019 85 HIM PRABHAT BRIDGE

Bridge No.87

Bridge 87 Abutment A-1: traversed by three plus joint sets with bedding as The bore hole drilled at chainage km 98031.00 prominent joint set. Partial (40%-50%) drill water loss reveals over burden material up to 3.50m depth recorded from 0.0 - 29.0m depth and water level is not comprises of angular to sub angular, cobble, pebble size met in the borehole. fragments of Sandstone mixed with silty clay, Cyclic plate load test has been conducted at Bridge unconsolidated in nature and interpreted as slide cum No.87 A1 .The plate test was conducted at a depth of 12 slope debris material. m BGL below existing ground level at (RL 1263.2m ) The bedrock encountered at 3.50m depth comprises .At this location stratum consists of completed fresh to slightly weathered, partial to highly fractured, disinterred ,weathered ,fractured ,light grey to reddish moderately strong to strong, well bedded, jointed, greyish brown ,weathered siltstone and sandstone . Cyclic PLT Sandstone interbedded with weak to moderately strong, was conducted between 21th&23th sept. 2016, total reddish brown Siltstone and weak soft reddish Claystone settlement of test plate under the action of 55.86 T/m2 with minor shear seams. Staining and coating along the applied pressure is 5.79 mm .The bridge foundation at structural planes has also been observed at places. Calcite this location is expected to undergo a total settlement of veins also noticed. The same strata was observed and 11.59 mm under 55T/m2, as permissible settlements for authenticated during pit mapping. bridge foundation are order of 12mm, the expected The core recovery in bed rock varies from 32% to settlement of 11.59 mm under a loading of 55 T/m2 is 100% and R.Q.D. from Nil to 58%.The rock mass is within permissible limits.

HIM PRABHAT 86 AUGUST 2019 BRIDGE

Bridge 87 Abutment A2: jointed, grayish Sandstone interbedded with weak to The rockmass condition exposed at the location of bridge moderately strong, reddish brown Siltstone and weak soft No.87A2 near chain age Km 98/274 is represented by reddish Claystone Staining and coated along the alternate bands of highly sheared fractured sandstone and structural planes is seen at places. The same strata was siltstone with clay partings. observed and authenticated during pit mapping. The frequent change in geological condition is Because of weak foundation geology of abutment A2 observed due to highly folded nature and nearness to of bridge 87, Pressure grouting was done to strengthen the major tectonic feature i.e., Murree thrust passing in the foundation keeping all design parameters in consideration. vicinity of the area.RQD is less than ?25 percent. The pressure grouting was done 20.00m deep having Spacing of discontinuities is <60mm with infillings 75mm ø at 1.5m c/c staggered below the foundation. of soft gouge .Persistence of discontinuities ranges from At site weathered rock was encountered at depth of 1 -10m, aperture opening varies from 1 -5 mm .Joints 23m BGL .The weathered rockmass at proposed are rough, undulated with clay infillings .shear seams founding level consisting of fine grained ,highly fractured are observed along the joints .Strike and dip orientation ,very closely jointed ,moderately hard ,grey sandstone are fair with respect to foundation .RMR varies from The rockmass is high sheared intensely crushed and 15 - 25, the rock mass belongs to the category of poor to fragile at most places with infillings consists of clayey very poor rock. material. At this location cyclic plate load test was carried Prior to excavation work, bore hole drilled at out on 27th Nov 2016 .Later on at same location static chainage km 98/274.262 reveals over burden material up PLT was conducted between 3rd& 4th December to drilled depth of 23.00m comprising of angular to sub 2016.The first PLT was test was stopped when total angular, Pebbles, cobble, boulders of hard grey Sandstone settlement of 50mm was observed under pressure of & Siltstone with clay matrix interpreted as slide cum 134.06T/M².In the second PLT conducted using larger slope debris material. The bedrock encountered at plat size, total settlement of more than 50mm was 23.00m depth is comprises of fresh to slightly weathered, observed under a loading of 135.84T/M².

AUGUST 2019 87 HIM PRABHAT BRIDGE

It can be summarized that at PLT location ,existing looseness or oversize of borehole in ground. Overview of stratum at a depth of 24m BGL (RL -1252.00 )is having PMT was given and the detailed discussion regarding safe bearing capacity of about 43T/M². PMT is beyond the scope of this topic. Standard Penetration test (SPT) for geotechnical At site weathered rock was encountered at depth of design purposes was done at Ch Km 98/587.850 ground 23m BGL .The weathered rockmass at proposed elevation 1252.603 m for every 1.50 meters from 0.00 m founding level consisting of fine grained ,highly fractured to 08.00m depth. Mostly the refusal of SPT was seen ,very closely jointed ,moderately hard ,grey sandstone during test. Penetration was 02cm in 33.00cm blows in The rockmass is high sheared intensely crushed and most of the test stretches. fragile at most places with infillings consists of clayey Three number of Pressure meter tests (PMT) was material. At this location cyclic plate load test was carried taken at 2.00m, 5.00m, and 8.00m intervals all through out on 27th Nov 2016 .Later on at same location static up to 08.00m depth.The test was done inside drill holes; PLT was conducted between 3rd& 4th December the objective of the test is to determine the in-situ 2016.The first PLT was test was stopped when total deformation modulus of the overburden soil/rock at settlement of 50mm was observed under pressure of respective depths in the drill hole through loading of the 134.06T/M².In the second PLT conducted using larger surrounding soil /rock up to a peak pressure of 70 or 80 plat size, total settlement of more than 50mm was bars. The test is usually used in geotechnical investigation observed under a loading of 135.84T/M². Allowable to know the stiffness or complete deformation due to Bearing capacity at this location can be taken as 128.69

HIM PRABHAT 88 AUGUST 2019 BRIDGE

T/M² =42.90 say 43T/M².Considering minimum of excavation starting edge is at RL :1250.0m ,bedrock 85.90 T/M²& 43T/M². ,it can be summarized that at encountered at foundation level 1210m .Hence the PLT location ,existing stratum at a depth of 24m BGL maximum height from bottom of foundation to (RL -1252.00 )is having safe bearing capacity of about excavation edge is 40m .The exposed walls after slope/ 43T/M². berm cutting on all the four sides are dominated by rocks with overburden layers at top. The walls are generally dry, Bridge 87 Pier No.1: but few seepage points & shear seams are also noticed The bore hole drilled at chainage km 98/095.722 reveals during geological mapping. The rock mass was highly over burden material up to 20.00m depth comprises of jointed, four number of joint sets are observed as follows angular to sub angular, Pebbles,cobble,boulders of hard as J1:55 - 60 /200 - 210 SW, J2:60 -70 /320 -330 NE, grey Sandstone &siltstone with clay matrix. The bedrock J3:40 - 45 /250 - 260 NE, J4:50-60 /340- 350 N. startsfrom20.00m onwards comprises fresh to slightly Standard Penetration test (SPT) for geotechnical weathered, jointed & fractured reddish brown to design purposes was done at every 1.50 meters from 0.00 grayish Sandstone interbedded with weak to moderately m to 15.00m depth. Mostly the refusal of SPT was seen strong reddish brown Siltstone and weak soft reddish during test. The penetration found was 03cm to 12cm in Claystone. Staining and coated along the structural 50 blows in most of the test stretches. planes has also been observed at places. Calcite veins also Plate load test has been conducted at Bridge No.87 noticed. The same strata was observed and authenticated P1. The proposed load was 214.4T/M². at 150kg /cm2 during pit mapping. of applied pressure, the average maximum settlement The rockmass exposed at location of Bridge 87 P1 found was 14.68 mm. From the results it can be near Ch: Km 98/410 is represented by alternate layers of summarized that PLT at 87P1, is having SBC of about thinly bedded sandstone, siltstone and claystone. The 70.0 T/M².

AUGUST 2019 89 HIM PRABHAT BRIDGE

Bridge No.87 Pier no.2: mixed with Silty clay matrix and interpreted as slide cum The rock mass exposed at bridge 87P2 near chain age slope debris material. The bed rock from 18m depth Km 98/474.1 is represented by alternate bands of thinly onwards comprises of mainly fresh to slightly weathered, bedded moderately to highly fractured moderately moderately fractured and jointed greyish Sandstone weathered medium to fine grained medium hard interbedded with weak to moderately strong reddish sandstone, siltstone and claystone .The exposed walls brown Siltstone. Intercalations of weak soft reddish after slope/ berm cutting on all the four sides are Claystone are also present at places. Staining and coating dominated by rocks with overburden at the top. The along the structural planes at places is also observed. bedrock is encountered at the foundation level 1214.5 m Standard Penetration test (SPT) for geotechnical which is 24 m from the excavation edge at RL design purposes was done at every 1.50 meters from 0.00 1238.0m.The four number of joint sets are observed ass m to 18.00m depth. Mostly the refusal of SPT was seen follows ;J1:40-50 /200 210 NE ,J2:50-60 /100- during test. Penetration was seen from 05cm to 23cm in 110NW,J3:45 - 55 /160-170 SW ,J4:40 -50 /320 - 50 blows in most of the test stretches. The Standard 330NE. penetration resistance or N - value ranges from 46 to The bore hole drilled at bridge no 87 P2 chainage 60.The SBC at bridge 87P2 is 70.0 T/M². km 98/160.462 reveals over burden material up to Pressure meter tests (PMT) was taken at every 3.00m 18.00m depth comprising of angular to sub angular, interval all through up to 42.00m depth.The test was cobble, pebble size fragments of Sandstone and Siltstone done inside drill holes at every3.00m interval, the

HIM PRABHAT 90 AUGUST 2019 BRIDGE

objective of the test is to determine the in-situ angular to sub angular, cobble, pebble size fragments of deformation modulus of the overburden soil/rock at Sandstone and Siltstone with silty clay matrix and respective depths in the drill hole through loading of the interpreted as slide cum slope debris material. The surrounding soil /rock up to a peak pressure of 70 or 80 bedrock encountered at 21.00m depth comprises bars. The test is usually used in geotechnical investigation alternate beds of fresh to slightly weathered, moderately to know the stiffness or complete deformation due to fractured, moderately strong to strong, jointed looseness or oversize of borehole in ground. Overview of brownish/grayish Sandstone interbedded with weak to PMT was given and the detailed discussion regarding moderately strong reddish brown Siltstone and weak soft PMT is beyond the scope of this topic. reddish brown Claystone. Staining along the structural Plate load test at bridge 87 P2 on 06.12.18 to planes is observed at places. Calcite veins also noticed. 07.12.18 was done in which static loading with proposed The same strata was observed and authenticated during test load of 214.5T/m2 was taken. At applied pressure of pit mapping. 271.7 kg/cm2 average settlement of 10.44 was found. Standard Penetration test (SPT) for geotechnical The SBC at Bridge 87 P2 was 70T/m2. design purposes was done at every 1.50 meters from 0.00 m to 32.00m depth. Mostly the refusal of SPT was seen Bridge 87 Pier No.P3: during test. The rock mass condition exposed at the location of Penetration was seen from 02cm to 27cm in 50 blows bridge no.87 P3 near chain age Km 98/538.929 is in some of the test stretches. The Standard penetration represented by alternate layers of thinly bedded sandstone resistance or N - value ranges from 22 to 91.The SBC at ,siltstone and claystone .Rock mass is thinly bedded bridge 87P2 is 70.0 T/M². ,moderately to highly weathered ,medium to fine grained Pressure meter tests (PMT) was taken at every 3.00m highly jointed grey sandstone and sheared siltstone and interval all through up to 32.00m depth. The test was reddish grey claystone. Clay infillings are observed in the done inside drill holes at every 3.00m interval; the rockmass with few quartz veins at places .The exposed objective of the test is to determine the in-situ walls after slope cutting on all the three sides are deformation modulus of the overburden soil/rock at dominated by rocks with overburden layer at the top. respective depths in the drill hole through loading of the Gentle warping in sandstone & siltstone layers is surrounding soil /rock up to a peak pressure of 70 or 80 observed. The excavation starting edge is at RL 1254m bars. The test is usually used in geotechnical investigation .Bedrock is encountered at foundation level 1237m .The to know the stiffness or complete deformation due to 17m from excavation edge. looseness or oversize of borehole in ground. Overview of The rock mass is highly jointed; five major joint sets PMT was given and the detailed discussion regarding are observed as follows J1:55-60/160-170S, J2:60 - PMT is beyond the scope of this topic. 65/025 -030N, J3:60-65/260-265W, J4:40-50/300- Plate load test at bridge 87 P2 on 06.12.18 to 310NW, J5:60-65 /225-235 SW 07.12.18 was done in which static loading with proposed The geological conditions correlates with the bore test load of 214.5T/M² was taken. At applied pressure of hole drilled at chainage km 98/225.202 which reveals 271.7 kg/cm2 average settlement of 10.44 was found. over burden material up to 21m depth comprising of The SBC at Bridge 87 P2 was 70T/M².

AUGUST 2019 91 HIM PRABHAT BRIDGE

HIM PRABHAT 92 AUGUST 2019 BRIDGE

CONCLUSION open joints. Such foundation location was tackled The paper has described the geological studies of major carefully and foundation improvement was carried out brides at Sangaldan. The area falls under the youngest before laying the PCC by pressure grouting method. The mountain chain of the world and the topography of this foundation which will be casted over a steep slope, the section is extremely rugged including steep hill slopes edge distance, frustum of bearing etc.have been checked with weak geological formation and is the most difficult as per IS codes. Excavation in open foundations has been zone of USBRL project due to its geomorphology and done after taking necessary safety measures. geological complexity. The area is witnessed by major Important concluding remarks on construction thrust known as Murree thrust which is tectonically validation having greater significance keeping the railway alignment The abutments & pier foundation would need to be crossing through it in the project area. The rocks of inspected and mapped by a qualified engineering bridge site belongs to Murree formation which are fresh geologist on site to confirm that the required ultimate to highly weathered, fragile, fractured and highly jointed geotechnical capacity can be achieved. In addition, two in nature and shows intense shearing, fracturing and boreholes of 10 m depth will need to be drilled to ensure folding at some locations due to Murree thrust, which that there would be any potential “Voids” below the pad leads to problems during open foundation excavation for footing founding level. The exposed cutting batters shall bridges. So slope protection as well as structure be mapped to ensure that any potential unstable wedges foundation stability is too important. Special attention will be stabilized. Similarly, the footing of the abutments has been taken during execution of cut slopes and shall be inspected and mapped by a qualified engineering foundation excavation on steep slopes to evade any geologist on site to confirm that the required ultimate untoward geological hazard. During slope cutting proper geotechnical capacity can be achieved. Attention shall be protection measures have been put in place for good paid to the sloping ground in front of the abutment to slope protection. The foundation which was found weak ensure that any potential unstable rock wedges will be got strengthened accordingly with pressure grouting as in stabilized prior to abutment construction. The exposed the case of Bridge no.87 A2. Standard geotechnical rock for the retaining wall construction shall be inspected procedures like standard penetration tests (SPT), and assessed by a qualified engineering geologist on site Pressure meter tests (PMT) and Plate load tests (PLT) to ensure that a “rough” surface as shown on the was conducted prior to raft concerting to ascertain Safe drawings will be achieved to avoid formation of any weak bearing pressure SBC at abutments and Pier locations. plane at the interface between mass concrete and the During execution of shallow open foundation of parent rock. Last but not the least before starting bridges, geological logging of the foundation area for construction work detailed geotechnical investigation is each abutment and Pier location have been carried out of paramount importance and will pave way for risk free properly and if found any shear zone/seams or weaker successful completion of projects. strata, necessary treatment for strengthening was done “Strength and weaknesses go together both in .At some places the nature of rock strata is noticed as matter and life. If nature has given weakness, nature poor to very poor rock , highly jointed, weathered with will compensate. No one is perfect.”

AUGUST 2019 93 HIM PRABHAT INVESTIGATION

REPORT ON THE GEOTECHNICAL ASSESMENT OF THE CRACKS AND SINKING DEVELOPED IN FRONT OF THE DUMPING YARD AT BUNI VILLAGE, KATRA - QAZIGUND RAIL LINE SECTION RAMBAN DISTRICT J&K

INTRODUCTION Construction work on the Rail line section in Sangaldan area was in progress at various sites i.e, tunnels, Sangaldan Station yard area and other ancillary structures. For the dumping of excavated muck an area measuring around 400m X 350m was selected in the Buni village Sangaldan .This area is bounded by two nallas, a perennial nallas which follows towards west and a seasonal nalla towards east. During the raining season their will be considerable flow in the nalla. The dumping yard is located on a spur between these two nallas.These nallas meet almost at the end of the spur DR. JOGINDER SINGH and flows further down and ultimately joins Chingi nalla a major drainage Consultant Geologist system in the area flowing from west to east .The spur is sloping towards KRCL - Reasi north with slope angle of around 25,º immediately below the dumping area, crates were erected to block the excavated dumped material from moving further down. The general angle of the slope is around 15-20º. (Photo: 1). The area along the spur is occupied by slope wash/ slope debris material represented by fragments and blocks of sandstone and siltstone embedded in soil. The material is semi-consolidated to unconsolidated in nature.

Photograph no.1: Showing dumping yard and two nallas on both sides of the sides of the dumping yard.

HIM PRABHAT 94 AUGUST 2019 INVESTIGATION

Visually estimated ratio of the coarse and fine material is around 45% - 55% respectively. The excavated muck from various sites is being dumped in this area within the dumping limits.

SLIDING/SINKING IN THE AREA On 20th of December 2013 some cracks were observed in the spur in front of the dumping area. As per the Geologists and site Engineers the cracks noticed were on small scale, which have widen considerably within a short period of time. The cracks are both along and across the spur (Photo 2, 3, 4 & 5)

Photograph no.2 & 3: Showing cracks along the spur in front of the dumping yard.

AUGUST 2019 95 HIM PRABHAT INVESTIGATION

Photograph no.4: Showing wide cracks along the spur in front of the dumping yard.

Photograph no.5: Showing horizontal cracks across the spur in front of dumping yard.

HIM PRABHAT 96 AUGUST 2019 INVESTIGATION

In the initial stretch these cracks were generally along of the Gulkhad nalla. Because of the free face available the slope and further down slope where the spur becomes towards nalla and thrust of the slided material from the narrow these were both along and across the spur, which right bank, the material was moved towards the nalla. The was a great matter of concern, if it continues to expand nalla bed was also uplifted at places and partially blocked endangering the whole area in the upslope. The spur at this the nalla. Small damming in the nalla have also been location forms steep scraps particularly along the right bank recorded in Gulkhad nalla (Photograph no. 6)

Photograph no.6: Showing small daming in the nalla.

AUGUST 2019 97 HIM PRABHAT INVESTIGATION

In the further down slope some small as well as a (photograph no. 8) More than 10m wide and 20m long huge trees wer uprooted and fallen in the seasonal nalla area along the center 0f the spur was sunk up to 2m, towards east of the spur (photograph no. 7) their by reducing the natural slope angle from 20º to 15º About 2m wide animal track was also damaged (Photograph no. 9)

Photograph no.7: Showing multiple cracks along the slope and uprooting of the trees.

Photograph no.8: Showing damaged animal foot track along the left bank of seasonal nalla Photograph no.9 (Two views): Showing sinking area by about 2mtrs in front of the dumping yard. INVESTIGATION

CAUSATIVE FACTORS REMEDIAL MEASURES During the visit of the area on 31st of January and 1st of The main causative factor for such a mass movement February 2014, it is observed that rain as well as snow appears to be charging of the area by surface run off and melt water following through the seasonal nalla coming nalla following behind the dumping yard. It was from further upslope area disappearing in the porous recommended then that nalla choked at places material behind the dumping yard (Photograph no.10) (Photograph no. 11) should be cleared and water tight The creeping of soil and falling of scree in the seasonal concrete lining up to considerable length along the nalla nalla from the bank slope during rains have choked this should be provided to check the nalla water from nalla adjoining to the dumping area which has also charging the area particularly during the raining season. added to the problem. The semi consolidated and Any other structure will not be useful for such a unconsolidated material gets lubricated when charged mass movement. Blockage in the Gulkhad nalla towards with water and loses its fractional resistance resulting into west of the affected area should be cleared and no the movement or settlement of the material along the damming of the water should be allowed. It was also slope under the influence of gravity. Till date no crack in suggested at the time that further dumping in the area the up slope area of the dumping yard has been observed. should be stopped immediately.

Photograph no.10: Showing water following through seasonal nalla which disappears behind the dumping yard

AUGUST 2019 99 HIM PRABHAT INVESTIGATION

Photograph no.11: Blocked portion of the seasonal nalla by the fallen material from the side was being cleared.

Further it was also suggested that cracks developed After implementation of some of the suggestions particularly along the slope should be filled with imperious made over five years back no further slumping / clay. The affected area should be made free of any water sinking in the area has been observed. Now some areas charging. No surface runoff from the adjoin area should be which appears to be more stable dumping of the allowed to flow over this area. Plantation of fast growing materials from some of the remaining sites is again trees should be carried out in the barren area upslope of continued. It is also suggested that after completion the dumping yard and in the affected area to avoid the soil of the dumping from various sites plantation in creeping or sliding in future. The protection work should the area as suggested above may be carried our be carried out before the onset of rainy season. immediately.

HIM PRABHAT 100 AUGUST 2019 000_COVERS.qxd 2/13/1950 7:25 PM Page 5

Bird’s eye view of approach viaduct of Chenab Bridge 000_COVERS.qxd 2/13/1950 7:25 PM Page 2

(Above) Chenab bridge Arch erection in progress. (Below): Bridge no.39 having 105m heigh Pier which is tallest in Indian Railways

DISCLAIMER Him Prabhat, USBRL technical news magazine is published in good faith and can not be held responsible in any way for inaccuracies in report / content that appear in this publication and the views of the contributors may not be those of the editors. The opinions expressed by this magazine are not necessarily the views of the editors/publisher, but of the individual writers. Unless specifically mention the articles and statements published in this magazine do not necessarily reflect the views or policies of Northern Railway, Ministry of Railways or Govt. of India.