In this part, first the origin and development of rock anchors are described. Their history began with a patent application in 1913 in Germany. The breakthrough in application came, however, only in the 1940s from the American mining industry. The first application of systematic rock bolting in a tunnel was the diversion tunnel for the Keyhole Dam in the USA in 1950. This paper describes numerous examples of civil engineering work world-wide with early application of rock bolting. It is shown how the combined application of the new support elements—steel arch, sprayed concrete and anchors has led to the ‘sprayed concrete lining’ method in the 1950s. In concluding, it is demonstrated that the so-called ‘New Austrian Tunnelling Method’ (NATM), which has been propagated since 1963, is in many respects borrowed and has created much confusion amongst professional engineers by dint of its pseudo-scientific basis.
The Longyou rock caverns are a group of large ancient underground caverns. They were caved manually in pelitic siltstone in the Quxian Formation of Upper Cretaceous. They have the following five characteristics: more than 2000 years old, man-caved, large spanned, near ground surface and medium to hard surrounding rock. They were unearthed by local farmers who were pumping water out of five small pools on a rough-flat ground in 1992. This discovery called the attention of many specialists from China, Japan, Poland, Singapore and USA. One of the most interesting and challenging questions is why the five caverns have been able to keep their integrity for more than 2000 years. To address this question, this paper presents the engineering geological conditions of the caverns and their adjacent areas. They include the following five conditions: (a) geological setting, (b) hydrogeological conditions, (c) seepage in integrity caverns, (d) fractures in integrity caverns and (e) failed caverns. Based on these investigation results, the paper further examines the potential failures of the integrity caverns and their protective measures.
This research aims at improving the methods of prediction of hazardous geotechnical structures in the front of a tunnel face. We propose and showcase our methodology using a case study on a water supply system in Cheshmeh Roozieh, Iran. Geotechnical investigations had previously reported three measurements of the newly established method of TSP-203 (Tunnel Seismic Prediction) along 684 m of the 3200 m long tunnel up to a depth of 600 m. We use the results of TSP-203 in a trained artificial neural network (ANN) to estimate the unknown nonlinear relationships between TSP-203 results and those obtained by the methods of Rock Mass Rating classification (RMR – treated here as real values). Our results show that an appropriately trained neural network can reliably predict the weak geological zones in front of a tunnel face accurately.
A 3D subsurface geotechnical model was developed for the Second Heinenoord Tunnel in a 3D-geo-scientific information systems (3D-GSIS) environment. The model is developed through the establishment of a 3D-subsurface model, a tunnel geometrical model, a 3D-grid (block) model, and the application of geostatistical modelling. The model was utilized for the analysis of tunnel boring machine geomechanical performance with a quantitative volumetric analysis. The study demonstrated the applicability of 3D-GSIS in modelling complex subsurface geological conditions, which is the case at the project site with soft heterogeneous Holocene top layers. The methodology followed is applicable for feasibility and engineering analysis, and may also be used for production estimation and model based simulation with a link to knowledge-based expert systems.
This paper presents a 3D numerical simulation of the mechanical behaviour of deep underground galleries with a special emphasis on time-dependent development of the Excavation Damage Zone (EDZ). The rock mass behaviour is modelled by a damageable viscoplastic constitutive law in which both viscous and damage parameters are taken into account. Finite-element analysis investigates the evolution of near-field stresses, progressive development of the damage zone as well as delayed displacements during the sequential construction process of the gallery. The influence of the orientation of in situ stresses with respect to the gallery axis is also highlighted. Moreover, the effect of a support system is shown to reduce the damage zone and the displacements around the gallery. The conclusion provides some guidelines for a computer aided analysis of the design of underground openings.
This paper includes a presentation of a simplified three-dimensional numerical model for the prediction of soil movement induced during tunnel construction using tunnel boring machines (TBM). The model is based upon the generalization of the convergence-confinement concept to 3D tunnel construction. It uses two parameters (Ldec and αdec) which stand for the length of the unlined zone and the partial stress release, respectively. The value of the parameter Ldec can be taken equal to the tunnel diameter, while the value of αdec can be determined by fitting the model to empirical formula, and then adjusted based on settlement registered during tunnel construction.The capacity of the model is illustrated through an application to a shallow tunnel in soft soil. The comparison of the numerical results to those suggested by different authors shows good agreement.
The assessment of the interaction between a new tunnel and existing structures is an important issue in urban areas. In this study, the effect of tunnelling on the existing support system (i.e. shotcrete lining and rock bolts) of an adjacent tunnel is firstly investigated using ABAQUS and TUNNEL3D through full three-dimensional (3D) finite element calculations coupled with elasto-plastic material models, which takes into account the tunnelling procedure, the interaction between the shotcrete lining and rock mass, the interaction between the rock bolts and rock mass, and the elasto-plastic behaviour of the rock mass, the shotcrete lining and the rock bolts. Then, on the basis of the calculated results, it is concluded that the driving of the new tunnel significantly affects the existing support system when the advancing tunnel face passes the existing support system and is minor when the face is far from it. Moreover, the support system in the side of the existing tunnel closest to the new tunnel is more significantly affected than that on the side opposite to the new tunnel. It is also found that in a region such as Sydney with relatively high horizontal regional stresses, the driving of the new tunnel will not cause considerable adverse effects on the existing support system, if the new tunnel is driven horizontally parallel to the existing tunnel with a sufficient separation, since both the tensile stress in the existing shotcrete lining in the lateral sides of the preceding tunnel and the compressive stress at the crown decrease although noticeable tensile stress increments are observed on some parts of the existing rock bolts. Finally, it is pointed out that the effects of tunnelling on the existing support system strongly depend on the position between the original and new tunnels. In terms of the stress increments on the existing support system, especially the maximum tensile stress increments on the existing shotcrete lining, the driving of the new tunnel causes increasingly adverse effects on the existing support system in a sequence of: (i) horizontally parallel tunnels with a separation of 30 m; (ii) horizontally parallel tunnels with a separation of 20 m; (iii) staggered tunnels with a separation of 30 m; (iv) vertically alignment tunnels; and (v) staggered tunnels with a separation of 20 m in the cases investigated in this study. For the relatively high regional stresses in the Sydney region, the obtained results qualitatively agree with other’s published observations from the construction of closely parallel subway tunnels.
In this work, a numerical 3D simulation of a longitudinal ventilation system (LVS) is developed to analyze the fire behaviour inside a road tunnel. The numerical modelling reproduces the Memorial Tunnel, a two-lane, 853 m long road tunnel, used for experimental purposes. On this tunnel, 98 full-scale fire ventilation tests with different ventilation systems were conducted, constituting the first significant experimental approach to analyze fire incidents inside road tunnels. A total number of 24 reversible jet fans were installed in groups of three, nearly equally spaced over the length of the tunnel, and cantilevered from the ceiling of the tunnel.The validation of a numerical model is developed in the present paper. For that purpose, the behaviour of the smoke generated during a fire incident inside a road tunnel is predicted and compared with previous experimental data collected in the Memorial Tunnel Project. The smoke evolution and the performance of the LVS is simulated with a commercial code, FLUENT, which allows 3D unsteady simulations of the Navier–Stokes equations for multispecies mixtures of gases. A sufficient mesh density was introduced for the spatial discretization in order to obtain accurate results in a reasonable CPU time. Hence, typical ratios between total number of cells and the overall tunnel length were employed in the modelling. As a result, good agreement was achieved in all the tested cases, defining an accurate methodology to predict the performance of a LVS in case of fire inside a tunnel.
Prediction of the tool wear and life, as well as secondary wear on machine components, in soft ground tunneling using shielded machines with a pressurized face has been a difficult task due to the lack of a universally accepted measurement system for soil abrasion. While some existing abrasion tests have been adopted in recent years to measure soil abrasion, these systems have inherent mismatches with the actual working conditions at the tunnel face. This paper reviews some of the background studies in this area and introduces the initial steps towards the development of a new soil abrasion testing system. The design and operational parameters for a proposed device that is under development for measuring a soil abrasion index are discussed and the preliminary results of testing on various soil samples are presented.Highlights► Soil abrasion has a major impact on soft ground mechanized tunneling but not well quantified in contract documents and source of delays and claims. ► Previous soil abrasion tests are reviewed and initial steps for developing a new soil abrasion index are discussed. ► The preliminary results of testing on various soils have been presented and showed a promise for future application in soft ground tunneling.
The abrasiveness of rocks is often described by the Cerchar abrasivity index CAI. However, the state of stress of the rock sample with the standard CAI test in the laboratory is different from the state of stress of rock to be excavated at the face of any underground opening. Until this work, no attempt has been made to estimate if and how the CAI is effected by in situ stresses. This paper demonstrates that the CAI is definitely stress-dependent. A novel test procedure in which the CAI tests is conducted on samples in a triaxial cell shows the stress dependency for various rock types by higher CAI values upon confining pressure. Additionally, the states of stress at the face of different underground openings are discussed and application of the elevated CAI values for estimating wear of roadheader picks and TBM discs is given.
Energy absorbing rock bolts are used as part of rock support systems in underground constructions that are exposed to e.g., rock bursts and detonating explosives. A rock bolt capable of absorbing kinetic energy from these loads must be able to yield with the ground movements and also deform plastically over large distances, at high displacement rates. A new type of energy absorbing rock bolt has been developed and tested in laboratory. The bolt is without a casing and consists of a steel bar that has an inner ribbed-like anchorage section and an outer nut that transfers the load from the rock via a circular disc. When subjected to a dynamic load, the lengthening of the steel bar leads to a decrease in diameter whereby the adhesive bond between bar and grout is lost and the outer end of the bolt is free to yield. The rock bolt is given a very good protection from corrosion when fully grouted in cement. In a laboratory, rock bolts in concrete cylinders were subjected to free fall tests to achieve a loading velocity of 10 m/s. The tests demonstrated that the distribution of plastic strain along the length of a grouted rock bolt is not constant when dynamically loaded. The sections where plastic yielding was allowed were not fully utilized in any of the cases, opposite to that in previous static tests which show almost constant elongation of the bolts. The tests also verified that the load-carrying components of the bolt, the nut and the anchorage, are reliable when dynamically loaded. Elastic and plastic waves will start to propagate through the rock bolt as it is suddenly loaded, resulting in permanent deformation along a section of the bolt. This yield process is demonstrated through a combined graphical and numerical method.
This report presents the results and output from a questionnaire undertaken by the ITA Working Group No. 4 regarding “Design Criteria for Access ways” to different types of underground structures. This theme was considered an important issue as the design and layout of access ways and installed mechanical equipment have great influence on construct ability and construction costs, maintenance and operation of the underground structures.The questions raised were basically dealing with the theme of access ways, but as well with the wider scope of design criteria for underground structures, such as: road (transport) tunnels; underground (metro) railway stations; underground parking areas and underground shopping malls and other facilities.ForewordThe theme of this report, design criteria for access ways to underground structures, was proposed by the representatives of Japan and Spain during the ITA Working Group No. 4 meeting, held in Sao Paulo in 1998. Around the globe an increased application of underground space has been experienced and the design of access ways is an important aspect of underground structures. The participants in the meeting in Sao Paolo, representing their member nations, supported the theme. Following the Working Group meetings in Oslo (1999) and Durban (2000) a questionnaire was prepared by Japan and Spain and distributed amongst the ITA member nations. The questions raised were basically dealing with the theme of access ways, but dealt as well with the wider scope of design criteria for underground structures, such as: road (transport) tunnels; underground (metro) railway stations; underground parking areas and underground shopping malls and other facilities.The main intention of the Working Group No. 4 Subsurface Planning was that the findings of the questions raised could be of great help in the field of assisting, developing and harmonizing subsurface planning.Not surprisingly, the member nations who replied to the questionnaires addressed the various aspects of this topic in different ways. Nevertheless, the diverse views clearly show differences in opinions and details by which various countries approach these issues. The report is intended to aid subsurface planners who wish to gain a broad view on how matters are dealt with in other countries or seek guidance in comparable situations – and also for the benefit and understanding of owners and operators of such facilities.The fire and life safety issues in road and railway tunnels are of course of great importance for public confidence in such structures. These issues have been specifically dealt with in a previous report by Working Group No. 4; “Fire and Life Safety for Underground Facilities” published in the journal “Tunneling and Underground Space Technology” (TUST), volume 13/3 July/September 1998.The ITA expresses the appreciation to the member nations who made contributions and especially to Japan who assembled and presented the material. The ITA also wish to thank Norway and the Netherlands for assisting in finalizing the report, which was completed under remaining Working Group 4 responsibilities.
Grouting as a mean to reduce the ingress of water to underground facilities has been used for decades. With an increased demand for tightness and cost efficiency, the incentive to improve the method has also increased, and the need to understand the governing factors has been focused. The knowledge concerning grouting involves several fields of research, for instance flow in fractured rock and the behaviour of the grouting material. An understanding of these fields is essential in grouting research. Numerical modelling of grout propagation in fracture geometries is one means of achieving such understanding. The paper presents how numerical calculations of grout spread and sealing effect can be used for predictions of the grouting result. The calculation concerns flow of grout in a network of conductive elements, representing a fracture geometry with the scope to understand the governing parameters when grouting. The spread of grout is significantly affected by the spatial variability of the fracture aperture. Measurements on grout properties and laboratory experiments show that the grout possesses a limited penetration ability and that filtration of the grout occurs if the aperture of a constriction is smaller than a critical value, i.e. when a filter cake forms in front of constrictions in the flow and the grout that passes is filtered. In the paper, a model for filtration of grout is presented. When filtration and limited penetration ability are incorporated in the calculations, additional strong effects are observed. This underlines the need of both a representative geometry, including the fracture variability, and measurements of grout properties.
The paper describes a system for assessing unambiguously the quality of tunnel blasting that can be used in comparing the working practices of different operations. The economic implications of blasting accuracy are analysed on the basis of data collected in actual operations. Drilling accuracy is identified as a primary factor in reducing tunnelling costs.
In this paper, the effect of seepage forces arising from the groundwater flow on the tunnel face stability was studied for underwater tunnels. The groundwater flow equation was solved and the seepage forces acting on the tunnel face were calculated using the upper bound solution in limit analysis. Especially, the effect of tunnel advance rate on the seepage forces and thus on the tunnel face stability was studied. A finite element program to analyze the groundwater flow around a tunnel with the consideration of tunnel advance rate was made. Example problem showed that the seepage force is greatly influenced by the tunnel advance rate in case of less permeable ground. Finally, a rational design methodology for the assessment of support pressures required for maintaining the stability of the tunnel face was suggested for underwater tunnels.
A considerable amount of tunnelling work has been going on in India for hydroelectric, irrigation, roads and railways projects. Most of these projects are located away from urban areas. The use of tunnelling for urban utilities, such as water supply, sewerage disposal and metro rail has recently begun. A few projects have been completed and some are under construction in metropolises such as Mumbai, Calcutta and Delhi. The present status of tunnelling and its future potential in India is highlighted in the paper with emphasis on tunnelling projects for hydro-power developments, as this sector presently has maximum underground construction activity in India. The tunnelling technologies for planning, design and construction have also been presented in this paper.
Impact type excavators are widely used for excavations, performed in weak-laminated-foliated-anisotropic rocks. Therefore the prediction of the performance of impact hammer is very important in many mining and civil engineering projects.This paper describes the construction of adaptive neuro-fuzzy inference system model for predicting the performance of impact hammer type excavator by considering rock and excavating machine properties such as block punch strength index, geological strength index system and impact hammer power. Extensive field and laboratory studies were conducted in the tunnel construction route of the second stage of Izmir Metro Project, which excavated in laminated-foliated flysch rocks. The results of the constructed adaptive neuro-fuzzy inference system and traditional multiple regression models were compared. Although the prediction performance of traditional multiple regression model is high, it is seen that adaptive neuro-fuzzy inference model exhibits better prediction performance according to statistical performance indicators. By means of the developed model, the performance of impact type excavators can be predicted in terms of net excavation based on the selected rock and machine properties.
 and  maintained that “tunnels should be driven full face whenever possible”. ADECO, which stands for “Analysis of Controlled Deformations in tunnels”, now allows us to fulfill Rabcewicz’s dream in any stress–strain condition. In order to achieve that dream and its consequent control over cost and schedule, however, NATM must be abandoned for the ADECO. The paper traces the history of the sequential excavation, NATM (as first conceived) and Analysis of Controlled Deformations (ADECO) with the aim of shedding light on the unavoidable use of sequential excavation in “soft ground”, and of highlighting advances in tunnel design and construction that have occurred in Europe after and as alternates to the NATM. The paper presents the basic concepts in the ADECO approach to design, construction and monitoring of tunnels together with some case histories, including: full face excavation for Cassia tunnel (face area > 230 m2) in sands and silts under 5 m cover below an archeological area in Rome, Italy; Tartaguille tunnel (face area > 140 m2) advanced full face in highly swelling and squeezing ground under 100 m cover where NATM led to catastrophic failure, France; and 80 km of tunnels (face area > 140 m2) advanced full face in highly squeezing/swelling ground under 500 m cover for the high-speed railway line between Bologne and Florence, Italy (turnkey contract).
A large excavation of approximately 140 m wide, 200 m long and 15 m deep was made close to two Mass Rapid Transit (MRT) tunnels of 6 m diameter with invert depth of 15–27 m. In view of the scale and distance of excavation, significant effects on the MRT tunnels were expected. The paper presents the monitoring of the tunnel deformations during the excavation. A sophisticated monitoring system using a motorised total station was installed in the MRT tunnels to monitor their displacements and to ensure that the stringent requirements for safeguarding the tunnels were not violated during any part of the excavation works. The paper also presents the modelling of the excavation using a finite element program. The results obtained were reasonably close to the monitoring results. It was found that the stiffness of the tunnel lining has significant influence on the displacement and distortion of tunnels caused by an adjacent excavation. A stiffer lining undergoes less displacement and distortion but is likely to experience significantly greater bending moments.
During the construction of the Taipei Rapid Transit System (TRTS) tunnels, a section of tunnel in the Panchiao Line was damaged as a result of adjacent excavation. Cracks appeared in reinforced concrete segments, the concrete slab on the invert was displaced and became detached from the segments. The event is a valuable case history for establishing criteria regulating excavations to be carried out adjacent to existing tunnels.
At the request of the Executive Committee of the International Tunnelling Association (ITA), the Working Group on Subsurface Planning of the ITA undertook a questionnaire survey of ITA member countries to examine legal and administrative issues relating to ownership of subsurface and restrictions on its development. Nineteen responses were received from mailings to thirty-five ITA member countries. This report summarizes these responses as they pertain to the following issues: Limits of Surface Property Ownership; Restrictions on Natural and Mineral Resource Exploitation; Ownership and the Right to Develop Subsurface Space; Major Permits Required; Application of Surface Land Use Regulations; Environmental Controls; and Restrictions due to Surface and Subsurface Structures. An ITA policy statement on subsurface planning also is included.RésuméA la demande du bureau exécutif de l'AITES, le groupe de travail “Utilisation du Sous-Sol” a fait circuler un questionnaire interrogeant les pays membres de l'AITES afin d'examiner les problèmes légaux et administratifs se rapportant à la question des droits de propriété des souterrains et des restrictions soumises à leur exploitation. Dix-neuf réponses ont été reçues sur 35 questionnaires adressés par courrier aux pays membres de l'AITES. Ce rapport présente un résumé des résponse concernant les questions suivants: limites de droits de propriété au terrain, restrictions des exploitations des ressources naturelles et minérales, droits de propriété et droits de développement de l'espace souterrain, permis de construction principaux obligatoires, mise en place des régles sur l'utilisation dy terrain, protection de l'environnement, et restirction dues aux structures en surface et souterraines. Une déclaration sur la politique officielle de l'AITES envers le planning souterrain apparait également dans ce rapport.
Safety requirement and regulations on fire and ventilation for tunnels in the Hong Kong Special Administrative Region (HKSAR, formerly Hong Kong) are reviewed. Both vehicular and railway tunnels are considered. Vehicle emissions are important for vehicular tunnels and so discussions on carbon monoxide from petrol engines and particulates from diesel engines are reported. Better environmental control on air temperature, air velocity and air pressure are also discussed. Problems to be considered for future tunnel design along these two areas are identified.
The excavation process for a tunnel changes in terms of its service requirements, ground conditions and the stability of surface buildings in urban areas. When a tunnel is excavated, there will be settlement, which may cause damage to surface structures. To control and limit the settlement caused by tunnelling operations, there have been many tunnelling techniques proposed. Thus, in this paper, a number of Finite Element Method analyses were conducted to investigate the effects of different patterns for advancing the tunnel face on the settlement. The Heathrow Express Trial tunnel was constructed in accordance with the principles of the New Austrian Tunnelling Method (NATM). The settlement measurements taken during its construction were used to validate the results from the analyses undertaken. Three different face advance techniques were used during the construction of the Heathrow Express Trial tunnel viz. Twin sidewall excavation (TS1), single sidewall excavation (TS2), and Crown, Bench and Invert excavation (TS3). As the trial work proved that TS2 produced the minimum settlement above tunnel centreline, only TS2 was subjected to the FEM analysis in this research. In order to simulate TS2 correctly three types of excavation models were devised and the results compared to field measurements of TS2. For the FEM analysis the Hypothetical Modulus of Elasticity (HME) soft lining approach was used and a practical method to estimate HME is proposed for when it is used for different face advance sequences. Results proved that when the excavation pattern was changed, the HME value was also changed and settlement over the tunnel centreline changed in terms of the face advance pattern adopted.
With the planned length of 36 km, Ghomroud tunnel is one of the longest tunnels under construction in central Iran. About half or 18 km of this tunnel was excavated by a double shield TBM. Several adverse geological conditions encountered, consisting of ground squeezing and face collapse, hindering TBM performance, and caused several TBM stoppages and jamming. This paper presents the impact of ground conditions on machine performance based on the information obtained from field observations and geotechnical site investigations. As built geological conditions are described while the method and results of tunnel convergence measurements and their impacts on tunneling operation is examined. Based on the detail study of the available geological information and tunnel convergence measurements, it was evident that the existence of weak structures in rock mass resulted in high rate of the convergence, which was the dominant factor in the TBM jamming. Since it was not possible to make observation and measurements of geological parameters when working in a lined tunnel built by a shielded machine, an attempt was made to correlate TBM operational parameters and ground convergence. The preliminary result of the analysis has indicated a good correlation among machine’s operational parameters and tunnel convergence. If the system is fully developed, these parameters can be used as an indicator of the potential for high rates of convergence. An early warning on ground convergence is essential for taking precautionary measures to avoid TBM from getting jammed by squeezing ground.
The Äspö Hard Rock Laboratory (Äspö HRL) provides an important scientific and technical basis for the programme o f implementation and operation of a future deep repository for spent nuclear fuel in Sweden. A major milestone has now been reached with the completion of the pre-investigation and construction phases. The comprehensive research conducted has permitted valuable development and verification of site characterization methods applied from the ground surface, boreholes and underground excavations. The present database of the crystalline rock at the Äspö area is one of the most comprehensive databases in the world, containing data from a large number of investigation methods from the surface down to 1700 m below ground level.Site characterization in conjunction with construction work at Äspö has basically confirmed the pre-construction models. The work at Äsphas shown that such pre-construction models can be obtained for the studied key issues through the application of “standard methodology of good quality” for measurements, data analyses, modelling and evaluation The site characterization at Aspö has been a realistic “adress-rehearsal” that will be invaluable for planning and executing surface and underground site characterization for the deep repository for spent fuel in Sweden.
In tunnel excavation by Tunnel Boring Machine (TBM), it is difficult to grasp the ground condition ahead of and surrounding the tunnel face because the face cannot be observed during tunnel driving. This is the reason why it has not been possible to make the best use of high-speed excavation capability of the TBM, especially in ground under complex conditions. Thus, the TBM Excavation Control System was developed to realize the accurate prediction of the geological condition ahead of and surrounding the tunnel face simultaneously with excavation. The special feature of this system is that geostatistical techniques are introduced into the data analysis using both drill logging data from pilot boring and TBM driving data obtained during excavation, in order to improve the precision of the ground mapping.
The potential of geophysical probing methods in TBM tunnelling is discussed. Modern TBMs have made it possible to tunnel through a wide range of geological conditions. However, the development towards more complicated machines has raised prices and often causes delays before the machines can begin operating properly. If a reliable system were available, the machine could be given a simpler design and the tunnelling process could be continuously adjusted to the prevailing ground conditions without jeopardizing safety. Geophysical investigation methods such as seismics and radar now offer the possibility of monitoring ground conditions ahead of the tunnel face. An analysis of a number of TBM projects has shown that if certain requirements on the range and time of the investigations are fulfilled, probing can be integrated into the tunnelling cycle.RésuméLe potentiel de sondages géophysiques est discuté dans le cadre du creusement de tunnels à l'aide d'une machine à forer. Les machines à forer modernes ont rendu possible le creusement de tunnels à travers une grande varieté de conditions géologiques. Néanmoins le développement de machines plus modernes a entraînéles prix à augmenter et souvent engendre des délais que les machines puissent opérer de manière convenable. Si un système de sondage adéquat existait, la conception de la machine à forer pourrait être simplifié et le processus de creusement serait ajusté aux conditions locales du sous-sol de manière continue, et cela sans négliger l'aspect sécurité. Des méthodes de sondage gephysique, tels les méthodes sismiques ou le radar, offrent la possibilité d'obtenir les conditions du sous-sol àl'avant de la tête du tunnel. L'analyse d'un certain nombre de projets utilisant des machines à forer a montréque le sondage peut être intégré dans le cycle de creusement si certaines conditions sur la portée et la durée des sondages sont remplies.
Tunnel construction frequently makes use of radial displacements to monitor tunnel support performance, particularly in complex ground conditions. In recent years, absolute displacement monitoring methods have replaced the more traditional radial convergence measurements. It has been suggested by Schubert and Budil (1995) [The importance of longitudinal deformation in tunnel excavation. In: Fujii, T. (Ed.), Proceedings of the 8th ISRM Congress on Rock Mechanics, Tokyo, vol. 3. A.A. Balkema, Rotterdam, pp. 1411–1444.] that these near-face displacements could also be used to forecast the tunnel conditions ahead of the advancing tunnel face. This paper presents the results from a series of detailed three-dimensional analyses in varying ground conditions, which compares vertical (radial) displacements measured at the roof, vector orientations associated with these roof displacements and tunnel face displacements (extrusion). These numerical results suggest that in all cases vector orientation provided additional information not obtained from traditional radial displacements or face extrusion. If interpreted correctly the vector orientations could provide advanced warning of changing ground conditions in the vicinity of the tunnel face.
Predicting ground conditions ahead of the tunnel face has been one of the most important requirements of tunnel construction. This study investigates the development and application of a high resolution ultrasonic wave imaging system, which captures the multiple reflections of ultrasonic waves at the interface, to detect discontinuities at laboratory scale rock mass model. Ultrasonic wave reflection imaging based on A- and B-modes is obtained through stacking, signal compensation, demodulation, and display. Experiments are carried out by using horizontal scanning and new rotational scanning devices. Experimental studies show that the rotational devices are able to identify horizontal and inclined discontinuities and the cavity on the plaster block at a fixed location. Furthermore, two discontinuities including horizontal and inclined discontinuity planes are detected. The rotating scanning technique produces images similar to those obtained by the typical horizontal scanning technique. This study suggests that the new rotational technique can be an economical and effective tool for the detection of discontinuity on a rock mass for the investigation of the ground condition in front of the tunnel face.
The engineers can frequently encounter with the situation to select the optimum option among the alternatives related with mining operations. The optimum choice can be selected by the experienced engineers taking into consideration their judgement and intuition. However, decision-making methods can offer to the engineers to support their optimum selection for a particular application in the scientific way. The Analytical Hierarchy Process (AHP) is one of the multi attribute decision-making (MADM) methods utilizing structured pair-wise comparisons. This paper presents an application of the AHP method to the selection of the optimum support design for the main transport road, which has been planned for deep coal seam panels of Western Lignite Corporation (WLC) Tuncbilek in Turkiye. The methodology considers eight main objectives, namely: four different displacement values for determined history locations, factor of safety (FOS), cost, labour and applicability factor for the selection of support design. The displacements and stress values were obtained by using the finite difference program FLAC3D as the numerical studies have been widely used by the engineers examining the response of any opening in underground, in advance. After carrying out several numerical models for different support design, the AHP method was incorporated to evaluate these support designs according to the pre-determined criteria. The result of this study shows that such AHP application can assist the engineers to effectively evaluate the support system alternatives for an underground mine.
The end of iron-mining operations in France's Lorraine region has raised the problem of post-mining management. Collapses and subsidence have recently occurred in this region, which focused on the necessity to develop a specific methodology for risk zoning. The proposed methodology is based on the multi-criteria decision-aid approach called ‘ELECTRE TRI’, with aim to assign zones at risk into predefined classes. It allows experts opinions, qualitative and quantitative criteria and uncertainties to be taken into account.
It is desirable to evaluate new tunneling technologies before they are actually implemented. The Decision Aids for Tunneling (DAT) allow one to simulate tunnel construction and to study the effect of changes in tunneling technology. The effects on tunneling cost and time of potential changes in microtunneling and in tunneling with a full-face TBM have been investigated. After calibrating models of these methods using data from actual tunneling projects, various modifications were introduced, both individually and in combination. The study showed that improvements of individual aspects lead to maximum cost or time savings of 10% to 20%. Simultaneous improvements of several aspects can lead to cost and time savings up to 75%. In addition to these results, the study indicates that the DAT are powerful tools with which most effects on tunnel construction can be investigated.RésuméIl est souhaitable d'évaluer des innovations techniques en construction de tunnels avant de les appliquer. Les “instruments d'aide à la décision pour la construction de tunnels” (ADCT) permettent de simuler la construction d'un tunnel et d'étudier les effets de ces innovations. Dans cet article, nous avons examiné les effets de modifications techniques sur le coût et la durée de construction d'un tunnel construit soit par un microtunnelier soit par un tunnelier normal. Après une calibration des modèles représentants ces méthodes de construction avec des données provenant de projets actuels nous avons introduit plusieures innovations individuelles ou combinées. Cette étude montre que les améliorations individuelles ne permettent que des réductions de 10% à 20% des coûts ou des durées. Par contre, les améliorations qui combinent plusieures modifications réduisent les coûts et les temps jusqu'à 75%. On peut enfin ajouter que les ADCT sont des outils puissants avec lesquels la plupart des influences sur la construction de tunnels peuvent être examinées.
This paper explores the capabilities of neural networks to predict the air losses in compressed air tunneling. Field data from the Feldmoching tunnel in Munich were used in this study. In this project, compressed air was used to retain the groundwater and shotcrete was used as temporary support. The final permanent lining was installed in free air. The tunnel passed through variable ground conditions ranging from coarse gravel to sand and clay. Grouting, an additional layer of shotcrete and a layer of mortar were occasionally used to control the air losses. A back-propagation feed forward neural network was trained and used to predict the air losses from the Feldmoching tunnel. The results of the prediction of the air losses from the tunnel using a neural network were compared with the field measurements. Data from different tunnel lengths were used for training. In each case, the trained network was used to predict the air losses during the excavation of the rest of the tunnel. It is shown that, not only can a neural network learn the relationship between appropriate soil and tunnel parameters and air losses, it can also generalize the learning to predict air losses for very different geological and geometric conditions. It is also shown that data from a very short length (50 m in one case) of the tunnel (five data point only, in this case) may contain enough information for the neural network to learn and predict the air losses in the remaining (585 m) length of the tunnel with a good degree of accuracy. This can be of considerable value to tunnel engineers in control of tunneling operations and help them in preparation for possible changes in air losses with tunnel advance, with changes in ground conditions and tunnel geometry and with time.
Adoption of a tunnel pressure, and the required volume of air to maintain that pressure, are currently based on judgment or empirical formulae. The risks associated with leakage of air from tunnels are not addressed by these methods. Such risks include surface settlement, uplift of structures, and development of air paths to other structures and excavations. A principal reason for these shortfalls is that the path and zone of influence of the air leakage cannot be predicted. In view of the paucity of scientific guidance for predicting these, a numerical model has been developed that simulates the consequences of using compressed air in soils. The model uses the program ABAQUS in an iterative scheme by updating the data for subsequent steps until convergence is reached and the final steady-state equilibrium is obtained. This model is compared to available empirical methods for a simple two-dimensional case.
When a fire occurs in a long tunnel, smoke control is crucial for obvious reasons of safety. Ventilation and extraction systems have to be designed with accuracy in order to control the longitudinal motion of the fire-induced smoke and to extract it efficiently in a zone close to the fire source. This paper presents experimental investigations carried out on a small scale tunnel model (scale reduction is 1:20) to study the fire-induced smoke control by longitudinal and transverse ventilation systems. The experimental model is non-thermal and a buoyant release (a mixing of air and helium) is used to represent the fire smoke plume. The main objective of this model is to represent, as well as make possible, the duality between inertial forces (due to ventilation) and buoyant forces. Radiation and heat losses at the walls are not taken into account in this model. At first, the principle of the simulation is widely described. Then, some results are presented for both longitudinal and transverse smoke control by a mechanical ventilation. Finally, perspectives for future investigations are proposed.
A study is ongoing to evaluate the feasibility of CAES facilities in the Upper Midwest of the United States.RésuméUne étude est en cours pour évaluer la faisabilité du centre CAES dans la région du haut Midwest des Etats-Unis.
Auxiliary ventilation is performed by carrying intake or return air in ducts. The complete elimination of air leakage from or into the ducting system is impossible due to duct quality and numerous joints in ducting system. The auxiliary ventilation systems for long drivages often require the use of multiple fans. Fans are installed in series and separated from each other in fixed or variable lengths. There are many methods proposed for the analysis air flow problems in leaky ducts. Due to the lengthy calculations, computers are often needed to conduct the analyses. In this study, a method known as “series–parallel combination of the duct and leakage path” has been introduced and a computer program has been developed based on this method.In order to design the conditions of an auxiliary ventilated drivage, in situ measurement have been made in Western Lignite Enterprises (GLI) OMERLER underground coal mine (Turkey) and the related data necessary for this study was collected. The presently developed program was tested using these data, and it was found that the measured and calculated values are quite close.The effective operational parameters governing auxiliary ventilation have been investigated and the effects of these variables on the volume rate of air flow reaching long drivage face have been examined by using linear regression analysis. Finally, it was concluded that the increase of duct diameter has prime importance in achieving the adequate air flow to the face and that for the auxiliary fans considered in this study the selection of fan does not greatly affect the volume rate reaching the face in a long duct line.
The paper presents a case study of urban underground space (UUS) use in an area of Alexanderplatz in Berlin, Germany. The study analyses data on underground structures, as well as water supply, communications and sewerage. The focus of the study is quantification of UUS: volumes and depth of underground infrastructure, as well as functional use of underground structures. Data on UUS and land use has been collected in two case study areas, both of them include Alexanderplatz. The big case study area covers about half of a square kilometer and has about 700 thousand cubic meters of developed UUS. Main results are presented as diagrams: UUS use by function, distribution of underground infrastructure by depth, and volume of developed underground space per land area. Transport is the main function of underground structures in the area, and accounts for about 60% of UUS volume. Density of underground structures in the area is about 2–3 m.
Misalignment and breakthrough errors have been a threat for tunnelers for 2500 years, and they still represent a problem that has been studied in detail on the occasion of certain rather recent major tunnels.From these analyses precise formulae permitting to compute the uncertainties in tunnel alignment and the breakthrough error have been proposed. Since these formulae are complex, require geodetic details and do not permit direct estimation of the order of magnitude of these errors, the latter have remained an obscure point for non-specialists.In this paper we explain why such errors occur and, based on the theory of error propagation and numerical approximation techniques, we derive certain simple formulae which permit to predict the magnitude of errors in tunnel alignment and in breakthrough in three dimensions. These formulae are for simple horizontal tunnels, constrained by geodetic observations at one portal and indicate that errors broadly follow a cantilever-type pattern. In addition, hints on how these formulae can be easily extended to all other cases of curved, inclined, etc. tunnels are provided. In the case, however, of complex tunnels (for instance double tunnels connected with transversal segments) errors are smaller for their propagation is controlled by redundant observations.
This paper summarizes negative psychological and physiological effects associated with underground buildings, identifies design strategies to alleviate them, and evaluates the effectiveness of some of these design techniques. The focus of the paper is on deep underground space with limited connection to the surface environment. A case study of design strategies used in deep underground office space is presented, and two proposed projects that further illustrate design techniques for deep mined space underground environments are described.RésuméCet article récapitule les effets psychologiques et physiologiques négatifs associés aux bâtiments sous terre, identifie les stratégies de conception pour les réduire, et évalue l'efficacité de quelques unes de ces techniques de conception. L'article se concentre sur des espaces sous-terrains profonds avec peu de liens avec l'environnement de surface. Une étude de cas des stratégies de conception utilisées pour des bureaux sous-terrains profonds est présentée, et deux projets proposés qui poursuivent des idées de conception en environnement sous-terrain miné profond sont décrits.
After a brief presentation of the AlpTransit projects (Gotthard and Lötschberg base tunnels) special aspects of safety and health protection are discussed: access via deep shafts, rock pressure, ingress of water and mud, ventilation, cooling, fire protection, escape routes and rescue. Medical aspects of climate and ventilation are discussed as dust and diesel soot emissions, blast fumes and hazards resulting from the shotcreting process. The preparation of safety concepts and comments on the planning and drawing up of safety measures are presented.
Granite is commonly recognized as an ideal medium for underground construction. However, in the site investigation for Heimifeng Pumped Storage Power Station project, it was found that there are swelling behaviors induced by alteration in granite and eventually causing slaking and disintegration of rock blocks. The study shows that hydrothermal alteration in granite is primarily due to the intrusion of multi-phase igneous magma. The clay minerals, such as montmorillonite, chlorite, kaolinite, are the main causes for the swelling behavior of granite. In the exploratory adits, alteration was observed to occur mainly along faults or fractures in the rock masses and resulted in roof caving if water is present. Some of the highly altered borehole cores swell and crack within 24 h in water and eventually disintegrate completely. From the testing results on the samples, the maximum axial free swelling strain is about 1.2%, while the maximum axial confined swelling strain is around 0.1% with swelling stress less than 25 kPa. Under free swelling tests, 80% of swelling is completed within 24 hours. Under confined swelling condition, swelling process is completed within 1 h for some samples, with 80% of maximum swelling strain finished within around 22 h for most of the samples. Contraction of samples occurs after swelling completed. The strength of granite, reflected by deformation and elastic moduli, shear strength, decreases due to alteration. The deformation and elastic moduli are even lower compared to highly weathered rock. The shear strength is between that for highly weathered and slightly weathered rocks. The swelling characteristics of the altered rock present great challenges for support or lining during construction and operation stages. Support or lining shall be in place immediately after excavation. Since the rock may swell when encountering water, the shotcrete shall be designed accordingly. During the construction of access tunnel and caverns, water shall be drained in time. Drainage directly from surface shall be avoided so as to prevent floor heave.
Researches on rock dynamics related to a cavern development project for ammunition storage in Singapore have been carried out. The researches include the study of dynamic properties of rock material (strength, modulus, constitutive relations), dynamic normal and shear properties of rock joints, shock wave propagation across joints and through the rock mass, and dynamic response of the rock mass and structures in rock using the discrete element method. The results obtained from the research works provide the necessary input to the design and construction of the cavern project.
The use of engineering geological information systems consisting of geotechnical information obtained from site investigations and ground water levels forms a powerful new dimension in planning of tunnels with respect to anticipating hazards and design problems. A pilot study was initiated in 1986 to produce an engineering geological information system for a 4-km2 area of the west-central district of Amsterdam. The information system contained cone penetration profile data, as well as information on boreholes and groundwater levels. The system has been shown to work using standard database and mapping programmes to produce thematic maps which can be used in tunnel planning and design. Reference is made to the proposed north-south underground light-railway line for Amsterdam to provide planning examples for which such an information system would be of relevance. The fact that these two projects ran concurrently but covered different areas of Amsterdam only emphasizes the need for tunnel planners and engineering geologists to become more aware of each others' needs. Use of information systems in tunnel planning has been successfully undertaken for the recent aqueduct tunnels of London.
The new Amsterdam North/South Metroline will use several innovative tunnelling techniques unique in the Netherlands' tunnelling history. This paper describes the determining characteristics of the Amsterdam Metroline such as the presence of pile foundations, the tunnel boring technology, and the deep underground stations. The paper also deals with risk management and operational safety in underground space, as applied to this project.
Utilities are an integral component of the total transportation network comprising highways, railways, airways, and waterways, as well as pipelines, wires, and cables that transport people, goods, and public services. The perennial dilemma of mutual interference between utility lines and transportation networks could be minimised making use of utility tunnel systems. Utilidors most striking feature is that they house several types of power, water, sewage, communications, gas and other statutory services in an easily accessible space. Placing utilities in tunnels under public rights-of-way reduces the continual cutting of pavements resulting from utility burial practices and facilitates the installation, inspection, replacement, and maintenance operations. Utility tunnels and transportation networks may not be compatible at transmission levels. Highway systems are generally planned to avoid high-density areas insofar as is possible. However, where the location of utility networks coincides sufficiently with the highway routes, the situation becomes more favourable to the utility tunnel concept. This paper discusses how compatibility of utility system networks with highway system networks could be greatly improved by appropriate attention to utilidor systems in urban planning. A sustainable approach to the dilemma of where to locate utilities in urban streets and highways has become urgent as the need for services expands in our modern cities. Interference between the safety and flow of highway traffic and utility tunnel operation could be a problem unless adequate measures are undertaken.
Elastic solutions are presented to predict the tunnelling-induced undrained ground movements for shallow and deep circular tunnels in soft ground, by imposing the oval-shaped ground deformation pattern as the boundary condition of the displacement around the tunnel opening. The gap parameter is used to describe the displacement at the opening. The difference between uniform radial and oval-shaped ground deformation patterns on ground deformations is investigated and different definitions for ground loss are discussed. The applicability of the proposed analytical solutions is checked with five case studies. Generally good agreement of the predicted ground deformations can be seen with field observations for tunnels in uniform clay.
Friction forces usually constitute the main component of jacking loads. As a result of their increase with jacking length, it is these forces which limit the drive length. Therefore, it seems important to be able to quantify them accurately. The field monitorings, carried out as a part of the French National Project ‘Microtunnels’, have shown the effects of parameters such as lubrication, stoppages, deviation and overbreak on friction force values. Frictional stress, deduced from field monitoring, is compared with empirical results extracted from the literature and with the results of most frequently used calculation models.
An analytical model is proposed to predict the axial force of grouted rock bolt in the tunnelling design. The interaction mechanism of the rock bolt and the soft rock mass has been described according to their consistent displacement. Coupling and decoupling behaviors of the rock bolt around a circular tunnel have been analyzed. According to case studies, the theoretical prediction of the axial force agrees well with the in situ measured results. The installing time and the length of the rock bolt, and the deformation modulus of the rock mass are taken as study parameters to analyze the supporting behavior of the rock bolt. According to the results of the theoretical analysis, there are some conclusions as followings: (1) a lower axial force is resulted because of the delay of installing rock bolt and its supporting effect may be reduced; (2) the larger displacement is caused by the lower deformation modulus of the rock mass, and a higher axial force is resulted in the rock bolt. If the shear strength of the rock mass is not enough, the decoupling behavior will take place interior the rock mass, and the performance of rock bolt may be reduced; (3) the position of a neutral point is related with the radius of tunnel, the physical properties of the rock bolt and the rock mass. It is found that the position of the neutral point and the maximum axial force of the rock bolt installed in the soft rock may tend to be constant when its length is long enough, which means that the supporting effect of the rock bolt can not be improved significantly only by increasing the length of the rock bolt. By using this model, a way is supplied to analyze the supporting behavior of the rock bolt, and a method is provided for the quantitative evaluation of its supporting effect in NATM tunnelling.
This study deals with the comparison of existing analytical solutions for the steady-state groundwater inflow into a drained circular tunnel in a semi-infinite aquifer. Two different boundary conditions (one for zero water pressure and the other for a constant total head) along the tunnel circumference, used in the existing solutions, are mentioned. Simple closed-form analytical solutions are re-derived within a common theoretical framework for two different boundary conditions by using the conformal mapping technique. The water inflow predictions are compared to investigate the difference among the solutions. The correct use of the boundary condition along the tunnel circumference in a shallow drained circular tunnel is emphasized.