The Stability of Tunnels in Grouted Fault Zones PDF Download

Author: Georgios Anagnostou
Publisher: vdf Hochschulverlag AG
ISBN: 9783728128744
Category : Technology & Engineering
Languages : en
Pages : 172

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Author: Florence Mezger
Publisher: vdf Hochschulverlag AG
ISBN: 3728140058
Category : Technology & Engineering
Languages : en
Pages : 361

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On the variability of squeezing behaviour in tunnelling

Author: Sara Zingg
Publisher: vdf Hochschulverlag AG
ISBN: 3728138193
Category : Technology & Engineering
Languages : en
Pages : 228

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This PhD thesis investigates the effectiveness of drainage measures with respect to two particularly important problems associated with tunnelling through water-bearing, weak ground: the stability of the tunnel face and the stability and deformation of grouting bodies. Water is an adverse factor with respect to the stability and deformation of underground structures due to the pore water pressure and the seepage forces associated with seepage flow towards the tunnel. Drainage boreholes reduce the pore water pressure and the seepage forces in the vicinity of the cavity. Furthermore, loss of pore water pressure increases the effective stresses and thus the shearing resistance of the ground („consolidation“), which is favourable in terms the deformation occurring during and after tunnelling. The goal of the PhD thesis is to elaborate a more detailed understanding of the interrelationships between drainage measures and the stability of the tunnel face and grouting bodies. The main objectives of the investigations relating to the tunnel face are: 1. analysis of face stability through limit equilibrium computations taking account of the numerically determined seepage flow conditions prevailing in the ground after the implementation of drainage measures; 2. systematic investigation of tunnel face stability considering several different drainage layouts and working out designnomograms; 3. consideration of a series of aspects limiting pore pressure relief and thus the effectiveness of drainage measures and their impact on face stability. The main objectives of the investigations with regard to grouting bodies are: 1. a study of the stabilizing effect of the virtual case of ideal drainage on tunnel support and plastification in grouted fault zones in plane strain conditions; 2. a comparison with the stabilizing effect of real drainage layouts, i.e. when considering pore pressure relief due to specific drainage borehole arrangements; 3. application of the drainage measure both before and after the injection works. In summary, the contribution of this PhD thesis is the detailed investigation of the static effects of drainage measures during tunnelling in water-bearing ground with respect to the stability of the tunnel face and the grouting body as well as the supply of design aids capable of providing a quick assessment of face stability when considering a number of advance drainage schemes.

Author: Lawrence R. Eckert
Publisher: SME
ISBN: 0873353315
Category : Tunneling
Languages : en
Pages : 994

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"Taken from a collection of papers presented at the prestigious 2010 North American Tunneling Conference"--p. [4] of cover.

Author: Weijie Dong
Publisher: vdf Hochschulverlag AG
ISBN: 3728138606
Category : Technology & Engineering
Languages : en
Pages : 205

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Squeezing conditions in tunnelling are characterized by the occurrence of large deformations of the opening or high rock pressure that may overstress the lining. Squeezing is associated with poor quality rock. Tunnelling in squeezing ground involves great uncertainties. It is therefore very important to gain a better understanding of the underlying mechanisms. Triaxial testing is the main source of information in order to understand the mechanical features of squeezing ground. Despite the complexity of the squeezing mechanism and the behaviour observed under relatively simple loading conditions, most of previous research work and engineering design practice considers the ground as a linearly elastic, perfectly plastic material obeying the Mohr-Coulomb yield criterion. While the MC model is capable of predicting the final strength and post-failure volumetric behaviour of the squeezing rock, it cannot map some potentially important pre-failure features or the occasionally observed contractant plastic deformation. In addition, the MC model usually leads to an overestimation of the strength under undrained conditions, which is unsafe for tunnel design. The present thesis mainly addresses the influence of constitutive modelling on predictions about the response of squeezing ground to tunnelling in order to provide some general guidelines for basic engineering analysis. This objective is achieved by investigating the behaviour of squeezing rocks theoretically and experimentally, using samples from several tunnel projects, including the Gotthard base tunnel and the planned Gibraltar strait tunnel.

Author: Amin Askarinejad
Publisher: vdf Hochschulverlag AG
ISBN: 372813676X
Category : Science
Languages : en
Pages : 366

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Landslides triggered by rainfall cause significant damage to infrastructure annually and affect many lives in several parts of the world, including Switzerland. These landslides are initiated by a decrease in the effective stresses, and hence the shear strength of the soil, as a result of the increase in pore water pressure. The frequency of their occurrence is directly affected by the climatic and hydrological conditions in the region. Therefore, it is expected that the predicted rise in the number of extreme meteorological events, accompanied by the concentration of population and infrastructure in mountainous regions, will result in an increased number of casualties associated with landslides in the future. The main goal of this doctoral project was to study the effects of pore water pressure perturbations on the stability of unsaturated silty sand slopes and to investigate the mechanisms leading to the initiation and propagation of the shear deformations and eventually possible rapid mass movements. The behaviour of the test slope prior to the failure induced by the artificial rainfall event was investigated using analytical and numerical methods. The mechanical features of unsaturated soils and reinforcing effects of the vegetation were implemented in 2D and 3D limit equilibrium analysis. The possible depth of the failure surface was calculated based on these simplified models and was compared with the depth of the real failure surface in the landslide triggering experiment. The soil-bedrock interactions, in terms of the pattern of pore pressure distributions and their influence on stabilising or destabilising the slope, were studied and the results were compared to the field measurements.

Author: Jian Zhao
Publisher: CRC Press
ISBN: 0203840690
Category : Technology & Engineering
Languages : en
Pages : 882

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During the last two decades rock mechanics in Europe has been undergoing some major transformation. The reduction of mining activities in Europe affects heavily on rock mechanics teaching and research at universities and institutes. At the same time, new emerging activities, notably, underground infrastructure construction, geothermal energy develo

Author: Emilio Bilotta
Publisher: CRC Press
ISBN: 1000538737
Category : Technology & Engineering
Languages : en
Pages : 484

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The book provides a new, global, updated, thorough, clear and practical risk-based approach to tunnelling design and construction methods, and discusses detailed examples of solutions applied to relevant case histories. It is organized in three sequential and integrated volumes: Volume 1: Concept – Basic Principles of Design Volume 2: Construction – Methods, Equipment, Tools and Materials Volume 3: Case Histories and Best Practices The book covers all aspects of tunnelling, giving useful and practical information about design (Volume 1), construction (Volume 2) and best practices (Volume 3). It provides the following features and benefits: updated vision on tunnelling design, tools, materials and construction balanced mix of theory, technology and applied experience different and harmonized points of view from academics, professionals and contractors easy consultation in the form of a handbook risk-oriented approach to tunnelling problems. The tunnelling industry is amazingly widespread and increasingly important all over the world, particularly in developing countries. The possible audience of the book are engineers, geologists, designers, constructors, providers, contractors, public and private customers, and, in general, technicians involved in the tunnelling and underground works industry. It is also a suitable source of information for industry professionals, senior undergraduate and graduate students, researchers and academics.

Author: Yuko Yamamoto
Publisher: vdf Hochschulverlag AG
ISBN: 3728136409
Category : Science
Languages : en
Pages : 519

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Alpine permafrost exists at high altitude at lower latitudes, such as in the Swiss Alps. Accelerating climate change, including rising mean annual air temperature and extreme rainfall conditions in alpine regions induces permafrost degradation. The warming of permafrost causes accelerated creep of rock glaciers, due to increased unfrozen water content and higher deformability of the ice phase. Recently, the development of deepening depressions has been observed in several rock glaciers in Switzerland, and the changes in land surface characteristics and drainage systems may initiate slope instabilities in rock glaciers. The main aim of this thesis is to characterise the strength and stiffness of alpine frozen soil in rock glaciers. To this end, the geotechnical response, such as creep and failure of frozen soil was investigated through a triaxial stress path testing programme with novel measurement systems for detecting acoustic emissions and measuring volumetric change. In addition, the resistance to crack initiation and propagation was investigated through a beam bending test programme on rectangular artificially frozen soil specimens, using the acoustic emission measurement system. The evaluation of laboratory tests on artificially frozen soil specimens implied that the development of deep depressions in rock glaciers occurs through differential creep and thermal degradation, and that the rate of deformation has the potential to lead to instabilities in rock glaciers. A comparison of the simulation results with the experimental data demonstrated that the semi-coupled model was successful in simulating the most important aspects of the temperature-dependent stress-strain relationship for the frozen soil behaviour that was measured at the element scale. This thesis contributes to an understanding of the variations in geotechnical response of alpine permafrost, by investigating the behaviour of artificially frozen soil specimens experimentally and numerically with time and temperature under specific stress paths. However, further investigations are necessary to assess the long-term stability of rock glaciers affected by climate change.

Author: Bernd Imre
Publisher: vdf Hochschulverlag AG
ISBN: 3728133310
Category : Avalanches
Languages : en
Pages : 167

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