Tunnel Investigation and Groundwater Control

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Tunnel investigation and groundwater control

PUBLICATION Technology Department no. 107

Norwegian Public Roads Administration Directorate of Public Roads P.O. Box 8142 Dep N-0033 Oslo

Telephone +47 22073500 Fax +47 22073768

E-mail: [email protected]

ISSN 1504-5064 Publication no. 107 Tunnel investigation and groundwater control

Mona Lindstrøm Technology Department

Alf Kveen Technology Department

NORWEGIAN PUBLIC ROADS ADMINISTRATION TECHNOLOGY DEPARTMENT OSLO, TRONDHEIM 2005 2 TUNNEL INVESTIGATION AND GROUNDWATER CONTROL TECHNOLOGY DEPARTMENT Preface

This report presents, in a condensed form, the results from a research programme on tunnel investigations and ground water control. Although the starting point was related to Norwegian conditions, the problems are the same elsewhere and the findings generally applicable. We thus hope that this English editi- on will be of value to other professional dealing with planning and construction of transportati- on tunnels in rock.

TECHNOLOGY DEPARTMENT TUNNEL INVESTIGATION AND GROUNDWATER CONTROL 3 4 TUNNEL INVESTIGATION AND GROUNDWATER CONTROL TECHNOLOGY DEPARTMENT Summary

The results from this programme have provided B: Environmental concerns. The vulnerability of new information about methods to improve the environment, especially related to changes tunnel planning and construction, and is espe- in the groundwater table caused by the tunnel cially important to areas where lowering of the construction, is evaluated with the aim to deve- groundwater table may cause severe damage to lop methods to quantify accepted levels of lea- the surface and man-made structures. kage into a tunnel. Procedures and guidelines for various conditions are presented. The programme were divided into three projects: C: Pre-grouting techniques. A specific grouting A: Investigation methods. New geological and technique and strategy utilizing thick cement geophysical methods were tested for their grout is developed. This technique and strategy potential to locate the direction of joints and is a result of evaluation of grouting performan- weakness zones at depth, and the leakage ces in several recently built tunnels, and has potential, as well as efficient mapping of regio- proven to be efficient and give better control on nal structures. The methods were found to be the amount of water draining into a tunnel. valuable supplements to traditional procedures. Completed tunnels were studied in order to see if there were any relations between investigation efforts and problems during excavation, with the aim to establish the type and appropriate amount of ground investigation on a given tunnel project. This has resulted in general guidelines depending on the complexity and project phase of the tunnel.

TECHNOLOGY DEPARTMENT TUNNEL INVESTIGATION AND GROUNDWATER CONTROL 5 6 TUNNEL INVESTIGATION AND GROUNDWATER CONTROL TECHNOLOGY DEPARTMENT Contents

Preface ...... 3

Summary...... 5

Contents ...... 7

1 Introduction ...... 9

2 New methods for tunnel investigation ...... 11 2.1 Borehole inspection...... 11 2.2 Two-dimensional (2D) resistivity ...... 12 2.3 Geophysical survey from helicopter...... 13 2.4 Mapping by digital analysis ...... 13 2.5 Radar interferometry ...... 15 2.6 Measuring While Drilling (MWD)...... 15 2.7 Refraction seismic modelling...... 16

3 Adequate investigations for Norwegian conditions ...... 17

4 Tunnel leakage and environmental aspects...... 19 4.1 Numerical modelling ...... 19 4.2 Accepted leakage in natural landscape...... 21 4.3 Accepted leakage in urban areas ...... 23

5 Techniques for groundwater control ...... 25 5.1 Laboratory testing of grout cements ...... 25 5.2 Grouting strategies ...... 25 5.3 Natural sealing processes ...... 27 5.4 Water infiltration...... 28 5.5 Pre-grouting techniques ...... 28

Participating firms in the research and development programme (2000-2003): ...... 31

Publications: ...... 33

TECHNOLOGY DEPARTMENT TUNNEL INVESTIGATION AND GROUNDWATER CONTROL 7 8 TUNNEL INVESTIGATION AND GROUNDWATER CONTROL TECHNOLOGY DEPARTMENT 1 Introduction

Norway holds a long tradition in building trans- ground investigation and groundwater control portation tunnels. There is a total of 915 (850 was initiated. km) road tunnels on the road network, 315 km railway tunnels and 45 km metro tunnels. With It was decided to concentrate the a few exceptions, these are all tunnels in rock. efforts on three main subjects: A: Investigation methods. The suitability of The generally good rock quality in Norway has advanced geological and geophysical methods made drill and blast the main method of tunnel- in locating the direction of joints and weakness ling. Ground investigations are performed to zones at depth, as well as the leakage potential locate joints, faults and weakness zones in order of the rock. to evaluate the stability and the leakage poten- B: Environmental concerns. The vulnerability of tial of the rock mass. The ground investigations the environment, especially related to changes traditionally also include geophysical mapping, in groundwater level caused by the tunnel con- core and percussion drilling from the surface as struction and the leakage into the tunnel. well as exploratory drilling at the tunnel work C: Pre-grouting techniques. Improving the face. grouting technique and strategy to obtain better control on the amount of water draining into a In the later years one has become aware of the tunnel. environmental consequences of changes in the groundwater system.Tunnel projects with heavy The programme involved the Norwegian Public water inflow during and after construction have Roads Administration, the National Rail caused significant damage to surface areas. As a Administration, the Research Council of consequence, a research and development pro- Norway, as well as several contractors, consul- gramme focusing on improving the quality of tants and research institutes.

Figure 1 The Lunner tunnel, built at Rv 35 north of Oslo.

TECHNOLOGY DEPARTMENT TUNNEL INVESTIGATION AND GROUNDWATER CONTROL 9 10 TUNNEL INVESTIGATION AND GROUNDWATER CONTROL TECHNOLOGY DEPARTMENT 2 New methods for tunnel investigation

New methods, with the potential of locating hods was above the Jong – Asker tunnels, two and investigating zones that may be problema- railway tunnels 2.7 and 3.7 km long, just west of tic to tunnel excavation are tested. The type of Oslo. Due to risk of settlements which could methods range from satellite and aerial investi- cause damage in the densely built-up area, the gations to geophysical (geo-electrical) investi- requirements for water ingress was set to bet- gations below the surface. The main part of ween 4 and 16 l/min./100 m. This construction these tests were performed by the Geological project will be completed in 2005. Survey of Norway. The aim of investigations for tunnelling is to The new investigation methods have the poten- obtain the information that is necessary to esta- tial of providing more detailed information blish the excavation procedures, the design of about the relative rock mass quality and water- the appropriate rock support, water sealing and bearing zones below the surface. Results from costs in good time before the tunnel constructi- both new and traditional methods were evalua- on is under way. The new methods have proven ted. The tests of different investigation methods to be useful alternatives and supplements to tra- in the same area and during tunnel construction ditional methods, especially in areas where it is provided a direct comparison of the methods, of great importance to obtain detailed informa- and a precise evaluation of their ability to locate tion about rock mass quality and water-bearing water-bearing zones in the depth. zones. The methods are user-friendly and the costs are generally lower than for the existing The main test site was the area above the methods.The results and evaluations of the spe- Lunner tunnel near Gardermoen Airport north cific methods are summarized below. of Oslo. The 3.8 km long tunnel is situated below a nature reserve, including a lake. For this reason the requirements for water ingress to 2.1 parts of the tunnel was set to 10 – 20 Borehole inspection litres/minute/100 m (water leakage after pre- grouting). The tunnel opened in 2003. The The optical televiewer (OPTV) is basically a second test site for the new investigation met- video camera which is lowered into a borehole

Figure 2 Optical televiewer recording of a borehole, showing a 360º picture of the borehole wall with its structures and an analysis of the individual joints.

TECHNOLOGY DEPARTMENT TUNNEL INVESTIGATION AND GROUNDWATER CONTROL 11 Figure 3 Left: Example of presentation of data from OPTV logging along a borehole, with joint frequency and location of different groups of joints. Right: The diagram presents resistivity measured by probe in the same borehole, showing good correlation between the joints located by OPTV and zones with low resistivity.

of 70 – 160 mm in diameter. It provides detailed daries). Similarly can probes measuring electri- information about rock type boundaries and cal conductivity of the rock mass identify pos- orientation and character of structures through sible weakness zones along the borehole (see a 360º picture of the borehole wall (Figure 2). example in Figure 3). Instruments within the OPTV record the frequency, strike and dip and opening of the vari- Hydraulic test pumping of boreholes is useful ous structures cutting the borehole, and statisti- for identifying water bearing joints within the cal analysis of the data is presented in diagrams borehole, and may be an alternative to Lugeon- (Figure 3). The OPTV can be used as an alterna- testing. The results give the potential for water tive to core drilling and logging. leakage where the tunnel cuts these fractures and subsequently help to evaluate the need for Additional inspection methods are probes pre-grouting. which are lowered into boreholes with continuous logging of geophysical parameters which can be interpreted to reflect rock mass quality or 2.2 potential for water leakage. For example, mea- Two-dimensional (2D) resistivity surements of changes in temperature and electrical conductivity of the water may indicate Two-dimensional resistivity provides a view of open joints with inflow of surface water. the physical properties of the rock mass below Variations in natural gamma radiation may the surface, this has not been possible by using reflect variations in mineralogy (rock type boun- traditional methods of investigation. The resisti-

12 TUNNEL INVESTIGATION AND GROUNDWATER CONTROL TECHNOLOGY DEPARTMENT Figure 4 Resistivity profile from a section of the Lunner tunnel. Zones of low resistivity are further examined by borehole logging.

vity is measured by electrodes attached to cables ly high resistivity in the ground; above 5000 lying on the surface. By processing the data, an ohmm. image (2D profile) of the subsurface resistivity is obtained down to a depth of 120 m (Figure 4). However, the best resolution is achieved at 2.3 depths down to 50 – 70 metres. The results can Geophysical survey from helicopter be interpreted in terms of rock mass condition: high resistivity indicates good quality rocks Geophysical survey from helicopter was carried whereas zones of relative low resistivity may be out over the area where the Lunner tunnel is correlated with jointed rock masses or weakness situated. Magnetic, radiometric, electromagnetic zones. The interpretation of the results depends and VLF (very low frequency) electromagnetic on a good geological knowledge of the area data was collected. For all these methods, faults from field investigations and other methods. and weakness zones in the bedrock may appear as linear or curvilinear anomalies, also in areas The tests which were carried out in this project covered with sediments and vegetation. show the exellent potential of 2D resistivity in Confirmation of the specific structures is done tunnel investigation. With this method it is pos- by field geological and geophysical mapping. sible to locate zones that may cause problems The helicopter survey thus provides an efficient related to stability and inflow of groundwater, method for mapping of regional structures and in far greater detail than traditional refracti- which may influence the tunnel excavation. on seismic. The position of the zones relative to the proposed tunnel can be traced, and boreholes for further inspection of the critical zones can 2.4 be established exactly in order to obtain the Mapping by digital analysis maximum amount of relevant information. Digital topographic maps were tested for appli- Measurements above the Lunner tunnel gave cability to register regional geological structures. very good results, the profiles show clearly The digital topographic data is combined with zones which correlated well with mapped struc- other digital data such as satellite- or aerial pho- tures both on the surface and inside the tunnel tos and maps. By processing these data it is pos- during excavation, as well as with borehole log- sible to locate lineaments that may represent ging in the area. In other locations (Jong-Asker) rock boundaries, weakness zones or faults. some of the limitations of this method became clear. The lack of distinct results was probably An example from the Oslo region show regional due to both a generally low resistivity in the lineaments produced by digital analysis (Figure ground, and a high density of technical installa- 5). The lineaments appear clearly on the map, tions in the Jong-Asker area. As a rule, this met- also in areas covered with urban settlement and hod seems to work well in areas with a general- infrastructure. Thus, this method also provides

TECHNOLOGY DEPARTMENT TUNNEL INVESTIGATION AND GROUNDWATER CONTROL 13 Figure 5 Lineaments produced by digital analysis from the area near the Metro tunnel (T-baneringen) in Oslo.

Figure 6 Example of settlements over time of three buildings above the Romeriksporten tunnel. One building, at Ellingsrud (red triangle), shows a natural continuous settlement in the period 1992 to 1999. Two other buildings (Godlia and Hellerud) were unaffected until about 1995 when the tunnel excavation progres- sed below these houses. For about one year they suffered a settlement of 15 mm until the leakages in the tunnel were finally under control.

14 TUNNEL INVESTIGATION AND GROUNDWATER CONTROL TECHNOLOGY DEPARTMENT important information about regional structures potential for daily or weekly monitoring of an which is useful at an early stage in the tunnel area during a future tunnel excavation is not as planning, especially in densely built-up areas. good, since data are collected at an interval of 35 days. 2.5 Radar interferometry 2.6 Measuring While Drilling (MWD) As part of this project, satellite-based radar interferometry is evaluated as a method to iden- Measuring While Drilling is a relatively new tify and monitor settlements during tunnel con- technique to register rock parameters ahead of struction. Satellite images are available from the the tunnel work face during drilling. The instru- period 1992 to 2001 and further on from 2004, ments are installed on the tunnel drilling and provide very detailed historic data. Vertical machine, and provide automatic registration of displacements down to mm-scale are registered selected parameters. These data are then inter- with this method. An example from the area preted according to a pre-set scale which is cali- above the Romeriksporten railway tunnel, brated for the specific project. Examples are which suffered significant environmental dama- registrations of relative joint frequency of the ge during tunnel construction, was used as an rock mass and variations in hardness (Figure 7). illustration. Recordings from before, during and after tunnel construction show both buildings The method is still under development and is in that were affected directly by the construction, use on several new tunnel construction sites. It and buildings that had suffered a regular subsi- is a good supplement to engineering geological dence over a long period of time, unaffected by mapping in the tunnel. MWD also helps to the tunnel (Figure 6). One of the advantages secure the documentation of data from the tun- with this method is that it is possible to monitor nel excavation, and will improve the communi- a large area in detail, instead of displacement cation between work shifts. measurements on selected buildings only. The

Figure 7 Examples of registrations during tunnel drilling. Relative rock hardness (top), and relative fractu- ring (bottom) in roof and walls along a 200 m section of the Lunner tunnel.

TECHNOLOGY DEPARTMENT TUNNEL INVESTIGATION AND GROUNDWATER CONTROL 15 2.7 (Figure 8). This is a common interpretation of Refraction seismic modelling this type of feature, the ambiguous data leads to interpretations that tend towards the worst case Seismic refraction is widely used in tunnel inve- scenario. For a more realistic interpretation, two stigation, especially for sub-sea tunnels. The possible situations could be described from the method measures the seismic velocities in the data. Further improvements of the seismic underground, and the velocities may be inter- refraction method would be techniques to preted in terms of rock mass quality. Some of extract more information from the available the limitations with this method are well data. known, for example are interpretation based on the assumption that the velocities increase A second model, illustrating a loose cable lying downward – which is most often the case. over a cliff similarly leads to interpretations that Furthermore, the method will only provide seis- do not reflect the actual situation, for example is mic velocities in the uppermost few metres of a weakness zone placed below the steep cliff. the bedrock surface. This interpretation can be improved by a more accurate mapping of the sea-floor topography The Norwegian Geotechnical Institute carried prior to the refraction seismic measurements. out refraction seismic modelling to illustrate that the standard interpretation of the available To obtain more precise information about pos- data can be inaccurate. Synthetic seismic sible weakness zones, seismic tomography can models of a rock surface with a sharp depressi- be used. This method produces a two-dimensi- on without a weakness zone below were pre- onal image of the seismic velocities in a profile sented in a blind test to a professional interpre- between the sea floor and the borehole, alterna- ter of seismic data. In each case, a vertical weak- tively between two boreholes. ness zone was positioned below the depression

Figure 8 Example of a synthetic model (top) and the interpretation of the model data (bottom) with a major weakness zone located in the depression. Seismic velocities higher than 5000 m/s generally represent good rock mass qualities. Weakness zones usually have velocities lower than 4000 m/s.

16 TUNNEL INVESTIGATION AND GROUNDWATER CONTROL TECHNOLOGY DEPARTMENT 3 Adequate investigations for Norwegian conditions

21 selected Norwegian tunnel projects have water or urban settlements, accessibility to been analysed to work out recommendations on perform field observations. The different the appropriate amount (cost) of ground inve- elements are weighted and given a value stigations for tunnels and caverns with today’s reflecting low, moderate or high degree of requirements to the projects. The degree of dif- difficulty. This corresponds to the com- ficulty in collecting information on the ground plexity of the ground in terms of tunnelling quality has been applied in the evaluations per- and the type and extent of investigation formed. In addition, the requirements to the needed. safety of the actual project during construction • Demands to the structure. This parameter and use, its influence on the environment, plus reflects stability, possible risks during risks for encountering unpleasant tunnelling excavation, possibility to affect or damage situations determine the project’s investigation the environment, such as vegetation or class. buildings. The elements are weighted and given a value reflecting low, moderate or The definition of investigation class is based on high demands during construction and the guidelines in the Norwegian Standard NS- operation. 3480 ‘Geotechnical planning’. In NS-3480, the geotechnical project class is defined based on The analysis of the 21 selected tunnel projects evaluation of a damage consequence class and according to this system resulted in the recom- degree of difficulty of the project. The same mended amount of investigation for each inve- principle is used in Eurocode 7, which defines stigation class, presented in Figure 9. three geotechnical categories. For a standard Norwegian road tunnel the recommended, appropriate total amount varies In summary, the investigation classes which is between 2 and 10 % of the cost for blasting and developed in this project is defined by the follo- mucking out included rig (20 – 30 %). For sub- wing two parameters (Table 1): sea tunnels this value varies between 5 and 15 • Degree of difficulty. This reflects the engi- % plus 2 to 5 % for exploratory drilling ahead of neering geological conditions, extent of the tunnel working face during construction. weathering, overlying sediment deposits,

Table 1 The investigation classes (A, B, C, D) determined from degree of difficulty and demands to the structure. These parameters are deduced from evaluations of various elements (not given here)

Definition of a. DEGREE OF DIFFICULTY INVESTIGATION CLASS a1. Low a2. Moderate a3. High b. DEMANDS TO b1. Low AAB THE STRUCTURE b2. Moderate A B C b3. High B C D

TECHNOLOGY DEPARTMENT TUNNEL INVESTIGATION AND GROUNDWATER CONTROL 17 C (Subsea) Ground investigations ( % of excavation cost ) ( % of excavation

Tunnel length ( km )

Figure 9 Recommended amount of investigation (costs) for the investigation classes (A, B, C and D), given as percentage of cost for blasting and mucking out included rig, relative to tunnel length.

The requirements to the accuracy of the cost achieve more detailed information about the estimates in the various stages of planning ground conditions, which contribute to more (Table 2) determine the amount for each of the precise cost estimates. Well planned and execu- four investigation classes defined. ted investigations increase the knowledge of the ground and thus reduce the probability for It is important to stress that ground investigati- unforeseen problems. ons cannot reveal all structures in the ground; therefore it is always possible to encounter unexpected conditions. The new geophysical investigation methods have made it possible to

Table 2 Approximate amount of investigation for each planning stage, and the demands for accuracy in the cost estimates for each phase

PROJECT PHASE INVESTIGATIONS Demands to accuracy Distribution of cost estimate Initial stage ? 1 - 5 % Preliminary plan ± 30 - 40 % ? 7 - 15 % General planning ± 25 % 15 - 35 % Zone plan ± 10 % 25 - 60 % Construction plan, Tendering ± 10 % 10 - 30 %

18 TUNNEL INVESTIGATION AND GROUNDWATER CONTROL TECHNOLOGY DEPARTMENT 4 Tunnel leakage and environmental aspects

The background for initiating the research pro- ween a number of parameters. These include gramme was severe tunnel leakages during a the water balance in nature, hydraulic conducti- specific construction project, the Romeriks- vity of the rock mass and overlying sediments, porten railway tunnel towards Gardermoen the potential for settlements, the vulnerability of Airport. The leakages caused damage on the the vegetation and grouting procedures. surface, both to vegetation (Figure 10) and to buildings. The aim of this sub-project was to study the effects of groundwater leakage and 4.1 develop procedures to quantify maximum allo- Numerical modelling wable water inflow to a tunnel based on the possible or acceptable impact on the surface Modelling may be used to simulate the hydro- environment. The studies were carried out by geological conditions before and after tunnel the Norwegian Geotechnical Institute, the excavation, and to evaluate the relative impor- Norwegian Institute for Nature Research, the tance of the different parameters used in the Norwegian Centre for Soil and Environmental models. In this way, important information Research and Norconsult. about the groundwater conditions may be provided in an early stage in the planning process. The work involved a study of the correlations The hydraulic conductivity of the bedrock in between water leakage into tunnels, changes in Norway is generally low, with groundwater flo- pore pressure and damage to the environment, wing along joints and weakness zones.The use- both to vegetation and water sources and to fulness of numerical flow models will depend urban structures. The acceptable amount of on realistic geological and hydrogeological water inflow into a tunnel in a specific area can input data and the boundary conditions esta- be determined by studying the correlation bet- blished for the model.

Figure 10 The tarn Puttjern which is situated above the Rome- riksporten tunnel. It was nearly drained due to tunnel leakages, and later, due to response from neighbours, resto- red with grouting and permanent water infiltration (Photo: L. Erikstad).

TECHNOLOGY DEPARTMENT TUNNEL INVESTIGATION AND GROUNDWATER CONTROL 19 Several models are available for simulating in the model. In a preliminary study the model water flow in jointed rock masses. Two main was built to illustrate a typical landscape situati- types were tested in this project to simulate on with, in a vertical section, bedrock in a local groundwater flow, groundwater drawdown and depression or valley bottom, overlying sediment the effects of sealing the tunnel: layers and a water saturated area on top repre- o Two-dimensional models, where the rock senting vulnerable nature elements. mass is modelled as a homogeneous Simulations were performed to study how water material with average hydraulic conduc- inflow to a rock tunnel will affect the vulnerable tivity surface area. The simulations were performed o Three-dimensional model of water flow in with varying hydraulic conductivities of each of a fracture network, providing a more the layers in the model. The results indicate that detailed image of flow in the rock mass. relatively small changes in the groundwater table may have an impact on the water saturated zone on the surface. The thickness and type Experiences from 2D modelling and hydraulic conductivities of the individual Several example studies were performed to sediment layers are the most important parame- simulate groundwater flow and the effects of ters. For example, a clay layer will seal off the tunnel leakage and sealing in a homogeneous groundwater and cause less water inflow. The rock mass, in order to test the applicability of relative position of the groundwater table adja- this type of model. A zone of low hydraulic con- cent to the local depression will also affect the ductivity around the tunnel in the model repre- amount of water inflow into the tunnel. sents sealing of the tunnel by cement injection. The study shows that to avoid lowering of the groundwater table of more than a few metres, Experiences from 3D modelling the leakage must be kept at 1 - 3 litres/ minu- A 3D discrete fracture network model was used te/100 metres tunnel. This will require a high to investigate the groundwater flow and to pre- degree of sealing effort, corresponding to a very dict water inflow to a tunnel during excavation low hydraulic conductivity of the sealed zone. and after cement injection. The model was built by the Norwegian Geotechnical Institute using A second approach involves analysis of a local the computer program Napsac, which takes into area with hydrogeological parameters and the account the heterogeneities existing in the rock interaction with overlying sediments included mass.

Figure 11 Example of presentation of the steady state pore pressure distribution in a section of the Lunner tunnel. A: The pre-tunnel situation, with geological data and the model fracture network. B: Modelled effects of pore pressure change after tunnel excavation. The water will tend to flow towards low- pressure areas (blue).

20 TUNNEL INVESTIGATION AND GROUNDWATER CONTROL TECHNOLOGY DEPARTMENT The Lunner tunnel was chosen as a field case Tunnelling effects on because of its part in the research project and the groundwater table the large amount of data available from the field The effects of tunnel excavations on the ground- investigations. The numerical model covers an water table was shown by collecting data from a area of 550 m x 550 m along the tunnel (see number of wells in the close vicinity of recently Figure 11). It includes a fault zone which repre- built tunnels. As would be expected, groundwa- sents the boundary between hornfels and syeni- ter drawdown becomes less significant away te. Joints and faults observed during the field from the tunnels. Changes which are caused by mapping are included in the model, as well as the tunnels are not observed beyond 200 to 300 results from borehole investigations and metres from the tunnel axis. The available data Lugeon-tests. Small-scale joints were statisti- shows, however, no clear correlation between cally modelled, and used to generate a discrete leakage into the tunnels and the measured fracture network. groundwater drawdown. In general, leakages of more than 25 litres/minute/100 m tunnel causes The model provides a three-dimensional image significant drawdown of the groundwater table of the water flow in the rock mass, and more (more than 5 to 10 m), and a leakage rate of 10 accurate results compared with results obtained l/min./100 m or less causes a groundwater from 2D models.The limitation of the 3D model drawdown of 0 - 5 metres. is the need for computer power, which in this case have put limits to the size of the area of investigation. Saturated transient and steady state calculations were performed to predict the 4.2 amount of water leaking into the tunnel. The Accepted leakage results from the simulation show that water inflow is high, with a large drawdown of in natural landscape groundwater. This is mainly caused by the fault In order to evaluate the impact a tunnel excava- zone which contribute significantly to the frac- tion may have on the environment, it is neces- ture network in the model. sary to assess the value of the surface environment, its sensitivity to a drawdown of the The effects of cement injection of the tunnel was groundwater table and the risks of damage. The modelled by reducing the transmissivity of areas most vulnerable to damage due to draina- joints cross-cutting the tunnel. The results show ge are identified as those having a groundwater that a reduction in the leakage rate is observed table which is directly feeding water-dependent only after a significant reduction in transmissivi- vegetation and surface water. The vulnerability ty. An extensive injection of the fault zone was increases with smaller size of the precipitation shown by comparison to be more effective than area. Changes in the groundwater table may a moderate injection along the whole tunnel, also cause disturbance in the chemical balance although the leakages tend to increase on both of surface water due to erosion and oxidation of sides of the injected section of the tunnel. Before dried-up sediments, which can lead to a con- cement injection a leakage rate of 900 l/min./100 centration of ions, salts and particles in the body m was predicted in the fault zone, with a signi- of water. The vulnerability must be evaluated on ficant drawdown of the groundwater table, the basis of practical use of the water source, the which would in effect drain the model. biodiversity and the presence of water-depen- Reducing the transmissivity in the fault zone by dent vegetation. a factor of 200 will result in a leakage rate of 50 l/min./100 m, and a lowering of the groundwa- A mapping programme with systematic regi- ter table of 5 m. stration of the vegetation above several tunnels with documented leakages was carried out in Details of this study are found in Cuisiat et. al the course of this project by the Norwegian (2003).The simulations have so far indicated the Institute for Nature Research. The aim was potential for this type of numerical tool in tun- mainly to aquire new information about the nel planning. Further analyses are needed befo- relation between damage to vegetation and re this 3D model is ready for use on a major tun- tunnel leakages. Systematic field mapping were nel project. not performed previous to the excavation of these tunnels, and the mapping programme thus focussed on the registration of visible

TECHNOLOGY DEPARTMENT TUNNEL INVESTIGATION AND GROUNDWATER CONTROL 21 Figure 12 Partly drained lake above the Tokke hydropower tunnel. Seasonal leakages cause significant variations in the water level. (Photo: A. Often).

damage. Surprisingly little damage to the vege- tively thin layer of soil lying on top of crystalline tation was recorded in this mapping. Some magmatic or metamorphic rocks. effects of drainage are easily identified such as Local depressions in the terrain usually coinci- ground settlements and dried-out ponds des with lineaments such as weakness zones in (Figure 12), but for the most part damage to the the bedrock, and this combined information is vegetation is not evident. It was concluded from of importance both in finally establishing the the study that this may be due to the fact that tunnel route, decision of the excavation proce- the actual damage is unsignificant or is healed, dures and in the planning of sealing measures that damage to certain species is undetectable to protect the most sensitive areas. due to lack of pre-tunnel investigation or that the scale of detail in the registration is not the The evaluation of acceptable changes on the appropriate for this type of investigation. surface environment involves a definition of the value of sensitive vegetation or surface elements The areas most sensitive to groundwater draw- along the tunnel route. In addition to economic down as a result of tunnel excavation are gene- value, the (non-monetary) values can be classi- rally quite small compared with the area above fied in terms of: 1) Nature, including biodiversi- the total length of the tunnel. A method is pro- ty, 2) Recreational, and 3) Importance to local posed to locate potentially vulnerable areas and communities. The value of each element is gra- to classify the vulnerability of nature elements at ded according to a pre-set scale, for example the early stages of tunnel planning. The method according to local, regional or international involves an initial identification of the potential- interest, or high to low value. ly sensitive areas from regional mapping. Features such as local depressions in the terrain The accepted impact on the surface is not deter- are isolated, as these often contains water- mined by the leakage rate, as a relatively low dependent vegetation. The vulnerability of each leakage may cause severe damage in more sen- area identified is then classified by the size of sitive areas. The accepted consequences will be the local catchment area, for example calculated defined by the value of the area, for example a from digital hillshade models, and field map- high value implies a low acceptance level. The ping of the local geology and hydrogeology. level of acceptance for each area may be conver- ted into a maximum allowable leakage rate The method is well adapted to the most com- along the respective sections of the tunnel. mon geological situation in Norway, with a rela-

22 TUNNEL INVESTIGATION AND GROUNDWATER CONTROL TECHNOLOGY DEPARTMENT Procedure to determine accepted measures to seal the tunnel, in the areas leakage rate in sensitive landscapes where tunnel leakage is likely to cause The recommended procedure for establishing unaccepted changes or damage. leakage requirements or accepted impact in relation to consequences for the environment is summarized as follows: 4.3 • Overall analysis of vulnerable areas. Accepted leakage in urban areas Combined with a general risk assessment this gives an overview of the probability of The requirements on maximum water inflow changes and the size of the impact. This into tunnels in urban areas are related to pos- forms the basis for more detailed analyses sible soil settlements which may cause damage of selected areas. to buildings and other surface structures. • Both a regional overview and details of Experiences from Norway, collected by the specific areas are needed. Detailed investi- Norwegian Geotechnical Institute, show that gation is performed for the vulnerable the risk of damage is highest in areas where the elements. building foundations are placed on soft marine • Define a value for each of the vulnerable clay deposits. Groundwater leaking into a rock elements tunnel can cause significant reduction in the • Describe the accepted consequences based pore pressure at the clay/rock-interface, which on the obtained value leads to consolidation processes in the clay and • State a figure for accepted change in the subsequent settlements. This situation with groundwater table, or water level in open marine clay deposited on bedrock is found in sources. the Oslo region, which represents the most hea- • State a figure for accepted water ingress to vily populated area in Norway. Data from mea- the tunnel. Evaluate both with regard to the surements on pore pressure reduction at the length of the tunnel and for ingress clay/rock-interface and leakage rates are compi- concentrated to a shorter section of the led from a number of rock tunnels excavated in tunnel (least accepted change). the region; for roads, railway, metro and sewers • Define a strategy for possible adjustment of (Figure 13). the tunnel route, tunnelling method and

Figure 13 Correlation between pore pressure reduction ∆uF (m) above existing tunnels, and leakage rate, Q (in l/min./100 m). The data forms the basis for a recommended acceptance level for leakage in this type of rock/clay-underground, shown by a characteristic area (hatched).

TECHNOLOGY DEPARTMENT TUNNEL INVESTIGATION AND GROUNDWATER CONTROL 23 From the data in Figure 13 it is possible to pre- ficantly by leakage. Drawdown of the ground- dict the pore pressure reduction in clay deposits water table is shown to occur mainly in areas caused by a tunnel excavation. The data forms where the clay deposits have a limited extent or the basis for the recommended procedure to where the clay deposits are shallow. establish maximum allowable water inflow into a tunnel. The data indicate that an acceptable An accepted maximum settlement is related to limit to the leakage rate should be 3 - 7 the value and the type of type structures on the litres/minute/ 100 metres tunnel, which corres- surface. For example, two major construction ponds to a pore pressure reduction of 1 - 3 projects in Oslo have requirements to maximum metres (Figure 13). settlements in the sediments above the tunnel excavation sites of 10 mm and 20 mm respecti- The pore pressure reduction decreases with dis- vely, in order to keep the possible influence on tance from the tunnel, with an average of 2 surface structures to a minimum. metres per 100 m horizontal distance from the tunnel. The measurements are locally affected by the thickness of the sediment deposit, sedi- Procedure to determine accepted lea- ment types, joints and weakness zones present kage rate in urban areas in the rock and the extent of cement grouting in The recommended procedure for estimating the tunnel. The study shows that systematic requirements for leakage rate is based on the grouting is necessary to fulfil strict leakage measurements of pore pressure changes in the requirements.There is a clear correlation betwe- clay/rock-interface: en the grouting procedures used in the tunnels, • Specify accepted maximum consolidation the amount of grout cement used, lenght of the settlement in the ground above the tunnel boreholes and the resulting hydraulic conducti- • Produce a map of soil cover, type and thick- vity in the rock above the tunnels. Recently ness, along the tunnel excavated tunnels generally shows better results • Calculate settlements in terms of pore in terms of fulfilled requirements, mainly due to pressure changes for any sediment/clay- improved grouting techniques and materials. filled depression identified • Identify buildings exposed to settlements at The potential for consolidation settlements in the vulnerable sites, and calculate maxi- the sediments in relation to pore pressure mum allowable pore pressure change for reduction can be determined from soil sampling this area and laboratory analyses. Clay deposits generally • Establish requirements for sealing of the contain small amounts of water and the tunnel based on the acceptable pore groundwater table will not be influenced signi- pressure change above the tunnel.

24 TUNNEL INVESTIGATION AND GROUNDWATER CONTROL TECHNOLOGY DEPARTMENT 5 Techniques for groundwater control

Techniques for groundwater control are studied these materials. Testing of cements was perfor- in this project, with the aim of improving con- med by conventional laboratory methods, using ventional techniques and development of new the actual cement types used in the grouting of methods. Safe and efficient methods for sealing the Metro tunnel. In summary, the tests showed are of special importance in tunnels with strict that water/cement-ratios (w/c-ratios) higher requirements for water ingress.The best method than 1.0 result in too long hardening time, the by far, for sealing rock mass to reduce ground- control of the actual w/c-ratio is best done by water ingress to tunnels, is cement grouting measurements of density, and only fresh ahead of the tunnel work face (pre-grouting). cements (newly produced) should be used. Test The project activities included studies of grou- results gave no indications that the temperature ting strategies for pre-grouting of tunnels, proof the cement during grouting is of importance, cedures for both systematic grouting and grou- but the temperature of the injected rock may ting adapted to difficult geological conditions inflict on the hardening process. and complex tunnel design, as well as procedures for time efficient grouting. In addition, the A significant part of the project was the con- project evaluated natural sealing processes and struction of an apparatus for testing injection water infiltration. properties of grout cements. This work was carried out by SINTEF. The apparatus consists of As a result, a specific grouting strategy is syste- two parallel glass plates pressed in contact with matized, based on tests performed on site each other, one of the plates has tracks which during tunnel excavation, laboratory tests and a simulate joints. Cement suspensions are injec- compilation and evaluation of grouting perfor- ted between the glass plates and instruments mances in several recently built tunnels. The register the inflow (penetration) capacities of improved grouting strategy is very efficient and the cements. The aim of this test model is to give good control on the amount of water provide comparative results for different cement ingress to the tunnel after grouting. Also, the types, under similar and controlled conditions. grout materials used are environmental friendly The test model was not able to provide results cements. during the time span of the project, but is under further development to become ready for com- A major part of the work in this sub-project was mercial use. monitoring of grouting procedures and practical tests of grouting strategies in ongoing tunnel construction projects: T-baneringen (Metro tun- 5.2 Grouting strategies nel in Oslo), the Jong-Asker railway tunnels and the road tunnels Hagan and Lunner just north The project group carried out a test programme of Oslo. in cooperation with the builder and contractor of the Metro tunnel in Oslo, in connection with the grouting procedures during tunnel excavati- 5.1 on. The aim was to confirm the grouting techni- Laboratory testing of grout cements que that most efficiently provides sufficient sealing of the rock mass. Laboratory tests were performed for the documentation of the properties of cement types The Metro tunnel is 1240 m long and part of the used in tunnel grouting, and an evaluation of new Metro Ring system in Oslo. The rock over- the usefulness of performing laboratory tests on burden of the tunnel is between 5 and 25

TECHNOLOGY DEPARTMENT TUNNEL INVESTIGATION AND GROUNDWATER CONTROL 25 metres, and with a cover (0-20 m) of sediments was also confirmed by the laboratory (clay). Due to risk of settlements in the clay cau- experiments. Silica additives to the grout sing damage to buildings, the requirements for mix and improved pumping capacity make water ingress to the tunnel after grouting was injection of this thick cement grout between 7 and 14 l/min./100 m, and grouting possible. was performed for most of the tunnel. The tun- • A low water/cement-ratio requires high nel was completed in 2002. Tests of materials pressure pumping, up to 10 MPa, which and grouting methods were carried out along ‘kick’the grout into the finer joints and different sections of the tunnel construction site assures that the rock mass close to the adjusted to the rock mass quality, rock cover and tunnel is sealed. demands for water inflow (see Figure 14). • Different types of cement grouts were used under similar rock mass conditions and Some of the tests and results are listed below: requirements for water ingress. In this • An evaluation of grouting procedures particular tunnel, no difference in the proved that systematic pre-grouting of the results from standard cement and tunnel is more efficient than sporadic microcement was recorded. grouting. Sporadic grouting involves • Tests were performed of optimum grouting adjustment of the procedure based on time consumed compared with the total results from measurements of water excavation time and the result of grouting, leakage in probe holes, and the risk is that by adjusting the work procedures.The most water will seep towards non-grouted time efficient procedure would be a fast sections of the tunnel. A systematic construction progress, with the criteria for grouting schedule is both more time water ingress fulfilled from a single round efficient and it gives far better and more of grouting. The adjustments proved very reliable results. efficient when working through good rock • A water/cement-ratio lower than 1.0 is mass quality and not so strict sealing necessary to provide rapid and sufficient requirements. sealing, the ratio may be as low as 0.5. This

Figure 14 Example of results of the grouting of the Metro tunnel: water leakage and amount of grout cement along the tunnel route. Horizontal lines: red= pre-set requirements for leakage (in l/min./100 m), blue= measured water ingress after grouting. Amount of cement grout used: blue= microcement, red= standard cement.

26 TUNNEL INVESTIGATION AND GROUNDWATER CONTROL TECHNOLOGY DEPARTMENT The procedures which were followed during strategies under various conditions, equipment, excavation through a particularly difficult weak- materials, performances and final results are ness zone with strong water inflow is also well mapped and compared. The detailed results documented. The zone is 50 metres wide and from the mapping is listed in tables which have needed special attention on grouting procedu- proven to be of significant importance when res and rock support. The requirements for planning the grouting strategy for new tunnel water ingress to the tunnel as a whole was ful- construction projects. filled, with an average of 4.3 l/min./100 m. The exception was the weakness zone, where water The general conclusions from the experiences leakage is up to 8 l/min./100 m. As a result, are comparable to the experiences from the water- and frost protection measures are redu- Metro tunnel, such as the advantage of syste- ced for parts of the tunnel. matic, cement-based grouting, low water/ cement-ratios and high pressure pumping, as Documentation of grouting procedu- well as careful supervision of the grouting pro- res: mapping of experiences cedure with adjustments to improve both effici- A selection of eight newly built tunnels (7 in ency and a safe result. These conclusions form Norway, one in Sweden) are examined with the basis of the recommended pre-grouting regard to experiences from grouting of the tun- procedure (‘Active grouting’, see below). nels. The mapping procedure involved intervi- ews with on-site personel representing both owners, builders, consultants and contractors. 5.3 The selection criteria for these tunnels were Natural sealing processes strict requirements for water inflow (2-20 l/min./100 m), and carefully planned and well In Norwegian tunnels, water ingress tend to documented grouting strategies. The experien- decrease with time. In most cases this could ces with different types of rock, the grouting only be caused by natural sealing. Laboratory

Figure 15 The Tanum tunnel (Jong-Asker railway). Markings of injection holes in the tunnel work face.

TECHNOLOGY DEPARTMENT TUNNEL INVESTIGATION AND GROUNDWATER CONTROL 27 experiments were carried out by Aquateam with The conclusions from the evaluation are that the aim of tracing the sealing mechanism and to infiltration holes must be placed in bedrock, and find out if this mechanism can be put to practi- established as result of good knowledge of the cal use in tunnels. Water samples from a selecti- hydraulic conductivity of the rock mass and the on of tunnels were analysed; sub-sea tunnels nature of sediment deposits. Wells placed in and one land tunnel.The main results show that sediments are unpredictable and have occasio- the water leaking into the tunnels is rich in par- nally caused severe problems due to erosion. ticles of iron, and contain lesser amounts of cal- Furthermore, water infiltration should be used cium, barium and manganese. as a temporary measure during construction only. All of the permanent installations that are Laboratory testing showed that oxygen injected in use today were not planned as such, and had to sand columns containing Fe2+ caused oxida- to be kept in function due to insufficient sealing tion to Fe3+ and subsequent deposition of the of the tunnel or underground structure. These iron, the rate depending on the particle size wit- installations do not guarantee that the pore hin the column. The results of these tests are pressure is maintained and are costly due to the interesting, but further tests are needed to find unforeseen, long term, ‘indefinite’, operation out if water leakages can be reduced by accele- and maintenance. rating natural sealing processes. 5.5 5.4 Pre-grouting techniques Water infiltration Theoretical and empirical background for high- Groundwater infiltration is used to control the pressure grouting pore pressure temporarily during excavation of A theoretical and empirical background for tunnels. The reduction of pore pressure in sedi- high-pressure grouting is assembled for this ments due to water leakage into a tunnel may project by N. Barton and Associates. The report cause settlement and significant damage to the describes the problems, and some solutions, surface areas and to buildings. In this project, concerning pre-injection in jointed and faulted experience from water infiltration over 20-30 rock masses ahead of tunnels.The application of years is compiled in a report from the very high pressure pre-injection for sealing and Norwegian Geotechnical Institute. improving the stability of tunnels, has focussed

Figure 16 Grouting in the Hagan tunnel syenite

28 TUNNEL INVESTIGATION AND GROUNDWATER CONTROL TECHNOLOGY DEPARTMENT attention on the need for quantitative explana- In order to grout the small and scattered chan- tions of grout take volumes and on the effects nels, many short injection holes are needed. An on the rock mass, of the 5 to 10 MPa injection initial high w/c-ratio (c. 0.9) and microcement is pressures. The report provides explanations of used, with a final lower ratio and high pressure joint properties and change when the rock mass pumping. is subjected to high-pressure grouting of thick D. Rock masses with extremely open joints as a cement grout. result of fault zones or karst. Tunnelling in these rock masses will require extraordinary efforts, In conclusion, there is practical evidence and for example injection of coarse masses. It is empirically-derived support for increased seis- important to locate these zones at an early stage mic velocities, increased deformation modulus, so that the grouting procedure may be properly reduced deformation, reduced permeability, and planned. reduced tunnel support needs as a result of successful high-pressure pre-injection with stable ‘Active grouting’ cement grout. A recommended procedure for pre-grouting is presented, based on the results from this project Rock mass quality combined with the compilation of well docu- The quality of the rock mass will determine the mented and successful grouting results in vari- choice of grouting strategy.The rock masses that ous rock masses. The foundation for the appli- are most common in the bedrock of Norway are cation of this grouting strategy is an understan- here divided into four groups based on experi- ding of rock mass quality, grouting pressures, ences from engineering geology and their gene- cement properties, the amount of cement and ral properties during grouting. For each group, cement additives used, the geometry of the the number of injection holes, length of holes, grouting fan and the number of injection holes water/cement-ratios and cement types are in the tunnel work face. recommended, as summarized below. • Low water/cement-ratio combined with The rock mass is divided into the following high pressure pumping is the main con- categories: dition for successful grouting.The w/c-ratio A. Open joints with little or no clay filling, found should be as low as practically possible most frequently in sandstones, quartzites, sye- (down to 0.5) in order to obtain a marked nites, granites. The hydraulic conductivity of the pressure loss away from the tunnel. This rock mass is relatively high, and the rock mass assures that the cement is concentrated has low resistance to grouting. In general, few close to the tunnel. The pressure build-up and long injection holes are used, and low in each separate hole must be constantly water/cement-ratios. surveilled, with adjustments of the w/c- B. Jointed rock mass with joints partly filled to ratio based on the observations. The produce local channels. This situation is fre- pressure build-up should increase steadily quently found in gneisses, which represent a to allow a smooth cement inflow, and with major part of the Norwegian bedrock.The joints a final injection pressure as high as is are typically filled with clay minerals weathered possible (10 MPa is the maximum capacity from feldspar minerals. The rock mass is less of most of today’s pumps). easy to grout, and the injection strategy must be • The type of cement is adjusted to local adjusted to the local rock mass condition. The geological conditions, both standard procedure is generally an initial high w/c-ratio cement and the fine-grained microcement (c. 1.0) and relatively low injection pressures, are used. Additives of superplasticizers and towards a final low w/c-ratio and high pressure silica increase the flow stability of the pumping (up to 10 MPa). The high injection cement grout. It should be noted that with pressure is important in order to establish com- the cement grout mix and the pump munication between joints. capacity for handling dense masses, there is C. Dense, plastic rock masses represented by no longer need for the highly toxic metamorphic rocks such as mica schists, phylli- chemical grouts. tes and greenschists. Joints are typically filled • The tunnel is to be grouted from the sole with clay, and have small channels occuring on and upward. In this way, the water is narrow joints. The hydraulic conductivity of the pushed up and away from the tunnel. The rock mass is low, and grouting may be difficult. grouting is most efficient when using many

TECHNOLOGY DEPARTMENT TUNNEL INVESTIGATION AND GROUNDWATER CONTROL 29 holes and as long holes as possible. The holes must be placed both circling the profile and in the centre of the work face. The geometry and the length of the holes in the grouting fan must be adjusted to the local conditions. An initial situation with many holes is recommended, with an adjustment based on observations and adaptations to the rock mass condition on the site. Use of modern injection rigs with two or more separate grouting lines increases the efficiency. • Systematic grouting where the leakage requirements are strict have proven to give the best results. Where the rock mass quality is favourable, the grouting procedure may be adjusted to a more time efficient ‘factory’performance. • A successful sealing, with little or no water leakage into the tunnel will reduce the need for water- and frost protection and rock support measures. • Continuous supervision, control and adjustment of the grouting procedure as well as an experienced professional crew is the key to a successful result.

In conclusion: It is possible to build technically very complicated tunnels with total control on the groundwater by using systematic cement- based grouting ahead of the tunnel working face, based on the principles of active grouting. This is of particular importance in areas where the tunnel construction is not to cause unwan- ted environmental consequences.

30 TUNNEL INVESTIGATION AND GROUNDWATER CONTROL TECHNOLOGY DEPARTMENT Participating firms in the research and development programme (2000-2003):

Norwegian Public Roads Administration (www.vegvesen.no) National Rail Administration (www.jbv.no) Geological Survey of Norway (www.ngu.no) Norwegian Geotechnical Institute (www.ngi.no) Norconsult AS (www.norconsult.no) Multiconsult AS (www.multiconsult.no) Norwegian Institute for Nature Research (www.nina.no) The Norwegian Centre for Soil and Environmental Research (www.jordforsk.no) Norwegian University of Science and Technology (www.ntnu.no) SINTEF (www.sintef.no) Aquateam (www.aquateam.no) GeoVita Geotechnical Peak Technology AS N. Barton & Associates

Additional funding by: Research Council of Norway (www.forskningsradet.no) Oslo City Government NCC Anlegg AS Skanska AS Veidekke ASA

TECHNOLOGY DEPARTMENT TUNNEL INVESTIGATION AND GROUNDWATER CONTROL 31 32 TUNNEL INVESTIGATION AND GROUNDWATER CONTROL TECHNOLOGY DEPARTMENT Publications:

The results from the research programme are The following three reports are avai- presented in a total of 40 reports, and are sum- lable in english: marized in five Publications from the Beard, L.P. (2001): Norwegian Public Roads Administration, Assessment of geophysical anomalies near Directorate of Public Roads (Statens vegvesen Langvatnet, Lunner, Oppland Fylke. Statens Vegdirektoratet). These are available in vegvesen Teknologiavdelingen. Report no. 2247. Norwegian only. Cuisiat, F., Skurtveit, E. & Kveldsvik, V. (2003): Publications: Prediction of leakage into the Lunner tunnel No. 101: based on discrete fracture flow models. Statens A. Palmstrøm, B. Nilsen, K.B. Pedersen & L. vegvesen Teknologiavdelingen. Report no. 2318. Grundt (2003): «Appropriate amount of investigations for underground rock constructions». Dehls, J.F. & Nordgulen, Ø. (2003): Analysis of INSAR data over Romeriksporten. No. 102: Statens vegvesen Teknologiavdelingen. Report J.S. Rønning (2003): «New geological and geo- no. 2346. physical methods for tunnel investigations».

No. 103: K. Karlsrud, L. Erikstad & P. Snilsberg (2003): «Requirements concerning tunnel leakages and environmental aspects»

No. 104: B.H. Klüver & A. Kveen (2004): «Practical pre- grouting»

No. 105: M. Lindstrøm & A. Kveen (2004): «Tunnel investigations and ground water control. Final report».

TECHNOLOGY DEPARTMENT TUNNEL INVESTIGATION AND GROUNDWATER CONTROL 33 34 TUNNEL INVESTIGATION AND GROUNDWATER CONTROL TECHNOLOGY DEPARTMENT Publications from the Technology Department

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Norwegian fjord crossings why and how. index method). 44 p. 1980. H. S. DEIZ. Investigations for subsea tunnels a case history. 53. E. HANSEN, G. REFSDAL, T.THURMANN-MOE. Sur facing for low H. BEITNES, O. T. BLINDHEIM. Subsea rock tunnels. Prei n vesti- volume roads in semi arid areas. gation and tunnelling processes. 36 p. 1986. H. MTANGO. Dry compaction of lateritic gravel. 61. Plastic Foam in Road Embankments: T.THURMANN-MOE. The Otta-surfacing method. Perfor mance T. E. FRYDENLUND. Soft ground problems. and economi. Ø. MYHRE. EPS – material specifications. G. REFSDAL. Thermal design of frost proof pavements. G. REFSDAL. EPS – design considerations. R. G. DAHLBERG, G. REFSDAL. Polystyrene foam for lightweight R. AABØE. 13 years of experience with EPS as a lightweight fill road embankments. material in road embankments. A. SØRLIE. Fabrics in Norwegian road building. G. REFSDAL. Future trends for EPS use. O. E. RUUD. Hot applied thermoplastic road marking materials. 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Sluttrapport «Instrumentering, doku- of health risks of dust from asphalt wear). mentasjon og verifikasjon» («Instrumen tation, documentation N. RYGG. Miljømessig vegtilpassing (Environmental road adjust- and verification, final report») 100 p. 1998. ment). 52 p. 1992. 87. OFU Gimsøystraumen bru. Anbefalinger for inspeksjon, reparasjon 65. C. HAUCK. The effect of fines on the stability of base gravel. og overflatebehandling av kystbruer i betong (Recommendations A. A. ANDRESEN, N. RYGG. Rotary-pressure sounding 20 years for inpection, repair and surface treatment of costal concrete of experience. 24 p. 1992. bridges). 112 p. 1998. 66. R. EVENSEN, P. SENSTAD. Distress and damage factors for 88. OFU Gimsøystraumen bru. Anbefalinger for instrumentert korro- flexible pavements. 100 p. 1992. sjonsovervåknning av kystbruer i betong. (Recommendations for 67. STEINMATERIALKOMITEEN. Steinmaterialer (Aggre gates). 20 instrumental corrosion monitoring of costal concrete bridges). 60 p. 1993. p. 1998 68. Å. KNUTSON. Frost action in soils. 40 p. 1993. 89. OFU Gimsøystraumen bru. Hovedresultater og oversikt over slutt- 69. J. VASLESTAD. Stål- og betongelementer i løsmasse tunneler dokumentasjon (Main result and overwiew of project reports). 24 (Corrugated steel culvert and precast elements used for cut and p. 1998. cover tunnels). 90. J. KROKEBORG. Sluttrapport for Veg-grepsprosjektet «Veggrep på J. VASLESTAD. Støttekonstruksjoner i armert jord (Rein forced vinterveg» («Studded tyres and public health, final report». 52 p. soil walls). 56 p. 1993. 1998. 70. SINTEF SAMFERDSELSTEKNIKK. Vegbrukers reduserte transport- 91. A. GRØNHAUG. Tunnelkledinger (Linings for water and frost pro- kostnader ved opphevelse av telerestriksjoner (Redused tran- tection of road tunnels). 68 p. 1998. sportation costs for road user when lifting axle load restrictions 92. J. K. LOFTHAUG, J. 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SOIL MECHANICS AND TUNNEL TECHNOLOGY SECTION Postal address: MATERIALS TECHNOLOGY SECTION Norwegian Public Roads Administration, BRIDGE TECHNOLOGY SECTION Directorate of Public Roads, ADMINISTRATION Technology Department, P.O. Box 8142 Dep, Telephone +47 22073500 N-0033 Oslo, Norway

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Tunnel investigation and groundwater control

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