Prediction Of Instability And Ground Movements During Tunnel Construction In Non Homogenous Conditions
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Prediction Of Instability And Ground Movements During Tunnel Construction In Non Homogenous Conditions
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Author : Vasiliki Founta
language : en
Publisher:
Release Date : 2018
Prediction Of Instability And Ground Movements During Tunnel Construction In Non Homogenous Conditions written by Vasiliki Founta and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with categories.
Advances in tunneling technology, notably in the widespread use of closed-face tunneling boring machines, have reduced risks and greatly increased the productivity of underground construction projects. For shallow tunnels in 'soft ground', instabilities can create collapse mechanisms that propagate to the ground surface, while the prediction and control of tunnel-induced ground deformations remain a key challenge. These problems are especially significant for 'mixed face' conditions, where the tunnel boring machine encounters soils of contrasting mechanical and/or hydraulic properties. This thesis uses finite element simulations to investigate the control of face stability and ground deformations for shallow tunnels in soft ground. The primary control parameters of interest are the face pressures imposed by earth pressure balance (EPB) or slurry shield machines, and the grouting pressures used to control deformations around the tail void at the rear of the tunnel shield. Stability is evaluated by methods of (c-phi) strength reduction, for a range of ground conditions including i) undrained failure in low permeability clays with continuous and discontinuous (mixed face) strength profiles; and ii) drained shearing in high permeability sands above and below the water table, where the closed-face conditions at the tunnel face provide an impermeable membrane. The numerical results are synthesized into a series of generalized design charts for immediate application. Numerical simulations using 3D finite element models are also used to investigate the factors influencing ground movements for closed-face tunneling operations using a relatively simple elastic-perfectly plastic model of soil behavior. These analyses show that maximum surface deformations above the tunnel can be estimated by simple addition of constituent sources associated with the face pressure, shield shape (conicity), machine weight (buoyancy) and grouting pressure. The research proposes a simplified method for predicting the surface settlements based on analytical parameterization of the numerical results, enabling direct design of parameters for controlling ground deformations associated with tunneling for mixed-face conditions in clays. The proposed methodology for predicting ground settlement has been evaluated using data from three well-documented case studies: 1) Crossrail C300 beneath Hyde Park in London, where tunnels were bored through units of stiff clay; 2) Downtown Line DTL3 (C933) in Singapore where tunnels traversed an interface between stiff Old Alluvium and overlying soft marine clays; and 3) northern sections of the MTRA Blue Line in Bangkok, where tunnels were built below the interface between soft and stiff clays. The comparisons between computed and measured data from these projects show that the proposed generic design method achieves comparable agreement to site specific numerical simulations and empirical methods such as ANN. Further studies are now needed to extend the model for mixed face conditions with contrasting permeability.
Prediction And Interpretation Of Ground Movements Due To Tunneling In Stiff Clay And Impacts On Adjacent Structures
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Author : Evangelia S. Ieronymaki
language : en
Publisher:
Release Date : 2015
Prediction And Interpretation Of Ground Movements Due To Tunneling In Stiff Clay And Impacts On Adjacent Structures written by Evangelia S. Ieronymaki and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
Construction of large diameter tunnels is frequently accomplished by closed face tunnel boring machines (TBM) using a combination of face pressure and grouting around the precast lining in order to limit ground movements and potential damage to overlying structures. This thesis analyzes monitoring data from the Crossrail project involving twin tunnels construction using Earth Pressure Balance (EPB) machines in London Clay. The research focuses on the 'greenfield' response during tunnel excavation beneath Hyde Park. Far-field measurements of surface and subsurface ground movements were interpreted using 2D finite element analyses using a range of constitutive models with parameters calibrated to non-linear stress-strain properties measured in high quality laboratory tests on London Clay. The analyses optimize three input parameters corresponding to boundary deformations around the tunnel cavity, using a least squares fit to the measured ground movements. The results for the first tunnel (WB) show that even simple soil models are able to achieve good agreement with far field ground deformations, while more complex models (MIT-Si) can represent accurately movements occurring much closer to the tunnel lining and hence, provide a more reliable guide to deformation sources at the tunnel cavity. The study also shows how ground movements induced by the second (EB) tunnel were influenced by proximity to the completed WB tunnel. The results provide a comprehensive view of the ground movement pattern and a useful framework for understanding how ground response is linked to EPB control parameters that can be investigated using 3D finite element models. Comparisons with data from prior open-face shield construction of the Jubilee Line Extension (in similar ground conditions) show that there are pervasive differences in the magnitudes and cavity deformations modes associated with different methods of tunnel construction. The current analyses of soil-structure interaction consider the measured deformations of a concrete-framed structure, Avenfield House, caused by the twin Crossrail tunnels. The thesis proposes a simple elastic shear beam model of the structure and assumes that the cavity deformation parameters are uncoupled from the presence of the structure. The results demonstrate that deformations of the structure can be predicted using information from the greenfield ground response.
Prediction And Control Of Interaction Between Ground Building And Tunnel Construction Process
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Author : Dan Meng
language : en
Publisher: Springer Nature
Release Date : 2022-09-24
Prediction And Control Of Interaction Between Ground Building And Tunnel Construction Process written by Dan Meng and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022-09-24 with Science categories.
This book covers tunnel construction and building construction and design. It has two parts. Part one is for the engineering practice of the subway tunnel through the base of the building in typical geological conditions, to study the mechanism and law of building damage caused by stratum deformation by in-situ monitoring, numerical simulation and theoretical analysis methods. At the same time, the risk management of subway tunnel through the bottom of the building is discussed. Second part, in view of the excavation and unloading of the foundation pit and the main structure loading in the process of high-rise building construction, discusses optimization of the construction scheme, systematic evaluation of the safety of the existing tunnel and control measures combined with the engineering practice. This book provides a valuable contribution to the field of tunnel construction and design and construction of building for both the engineering experts and graduate students as well.
Analytical Prediction Of Ground Movements Due To Mrta Tunneling
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Author : Md Arifuzzaman
language : en
Publisher: LAP Lambert Academic Publishing
Release Date : 2010-10
Analytical Prediction Of Ground Movements Due To Mrta Tunneling written by Md Arifuzzaman and has been published by LAP Lambert Academic Publishing this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010-10 with categories.
This study presented here the prediction of the ground movements due to MRTA tunnel in Bangkok. The different boundary conditions and derivation techniques were the main characteristics of the analytical solutions and the difference between uniform radial and oval-shaped ground deformation patterns on ground deformations is investigated. Generally good agreement of the predicted ground deformations can be seen with field observations for tunnels in uniform clay. The method Park2 is yielding the best result for surface settlements. Also different parameters effect has been studied here to get some concrete relation. Lateral displacements could not be handled properly with the existing analytical solutions.
Ground Movements During Tunnelling In Sand
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Author : Jason Peter Thorpe
language : en
Publisher:
Release Date : 2007
Ground Movements During Tunnelling In Sand written by Jason Peter Thorpe and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with categories.
During soft ground tunnel construction, if the face pressure of a tunnel boring machine is not strictly controlled, excessive ground movements will propagate vertically upwards causing significant damage to adjacent buried infrastructure and surface structures. In order to investigate the face pressure - ground deformation relationship for tunnels in sands, the construction process was modelled using the technique of geotechnical centrifuge modelling and the resulting ground deformations were recorded using digital image correlation. In these tests a unique tunnel face boundary condition was developed which allowed the boundary condition to be initially set as a zero strain condition before it was transformed into a load-controlled boundary to investigate the instability of the face. Tests were preformed at four different burial depths in dry sand, corresponding to cover depths of 0.5, 1, 1.5, and 2 times the tunnel diameter. These results indicate that the face pressure at failure is largely independent of burial depth over the values tested. The ground deformation at the onset of tunnel face instability was found to be very small, and once initiated, the zone of ground deformations was observed to propagate upwards in a narrow chimney in front of the tunnel until it reached the ground surface causing subsidence. Further tests investigated the variation in ground deformations to be expected if a tunnel were to be passing through more complex ground conditions, including unsaturated sand, saturated sand, and the unique case of sand / clay mixed ground conditions. Ground deformations at tunnel face instability were much lower for the case of unsaturated sand, than for either the saturated or dry cases which showed broadly similar responses. In the mixed ground condition of a clay layer over topping a sand layer, the clay layer was found to only influence the tunnel face pressure - deformation response if the bottom of the clay layer was closer than 0.5 diameters above the tunnel crown.
Prediction And Effects Of Ground Movements Caused By Tunnelling In Soft
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Author : L. M. Lake
language : en
Publisher:
Release Date : 1996-12
Prediction And Effects Of Ground Movements Caused By Tunnelling In Soft written by L. M. Lake and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1996-12 with categories.
This book assists engineers with the assessment of the risk to structures from urban tunnelling in soft ground. It gives a full review of available precautionary measures to minimize the effects of tunnelling on structures services, together with comments on their range of applicability.
Prediction And Effects Of Ground Movements Caused By Tunnelling In Soft Ground Beneath Urban Areas
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Author : L. M. Lake
language : en
Publisher:
Release Date : 1996
Prediction And Effects Of Ground Movements Caused By Tunnelling In Soft Ground Beneath Urban Areas written by L. M. Lake and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1996 with Buildings categories.
Ground Movements Associated With Twin Tunnel Construction In Clay
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Author : Sam Divall
language : en
Publisher:
Release Date : 2013
Ground Movements Associated With Twin Tunnel Construction In Clay written by Sam Divall and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
The rising population in urban environments comes with an associated demand for increased public transport. Due to the level of surface congestion an often utilised solution is to construct rapid transit systems within tunnels. Any sub-surface construction will generate ground movements which have the potential to cause damage to existing surface and sub-surface structures. Urbanisation and congested cities have driven the need for accurate predictions of tunnelling-induced settlements and has produced many publications (e.g. Peck, 1969; Cording & Hansmire, 1975; Clough & Schmidt, 1981; O'Reilly & New, 1982; Attewell & Yates, 1984; Cording, 1991; Mair et al., 1993 and Mair & Taylor, 1997). Largely, however, these empirically based prediction methods are concerned with single tunnel greenfield, arrangements. Generally, mass rapid transport systems comprise of a pair of tunnels constructed within relative close proximity. This is known as twin-tunnel construction. A number of case studies have shown a relative difference in the settlements due to each tunnel construction (e.g. Cooper et al., 2002; Cording & Hansmire, 1975 and Nyren, 1998). These were further investigated by numerical studies which support these observations (e.g. Addenbrooke & Potts, 2001 and Hunt, 2005). Analyses that use isotropic linear elasticperfectly plastic soil models have tended to produce wider surface settlement troughs then observed by the Gaussian distribution (Mair et al., 1981). It is that clear valuable insight could be gained from a physical model based study. Therefore, a series of plane strain centrifuge tests was carried out investigating twin tunnelling-induced settlements in overconsolidated clay. Apparatus necessary to perform these tasks required a significant amount of time to develop and was relatively complex. The main variables were the spacing between the tunnels, both horizontally and vertically, and the magnitude of volume loss. The tests were conducted at 100g where the cavities represented two 4m diameter tunnels at (usually) a depth of 10m at prototype scale. The tests utilised novel apparatus designed during the research to enable the simulation of the construction processes related to volume loss in separate sequential tunnels. The results presented are in regards to the prediction of ground movements in the plane perpendicular to advancing tunnels and the significant findings of the research are as follows: - 1. Single tunnel surface and sub-surface settlement troughs are well represented by Gaussian distributions, however, the twin-tunnelling predictions can be improved by modifying the settlements solely due to the second tunnel construction. 2. The magnitude of volume loss from the new tunnel construction had increased due to the presence of the first tunnel. This effect was lessened by larger spacings between the tunnels. 3. Second tunnel settlements can be predicted using equations by Peck (1969), O'Reilly & New (1982) and Mair et al. (1993) but with the modifications. The surface and sub-surface settlement distributions towards the existing tunnel were observed to be wider than a single tunnel.
Introduction To Tunnel Construction
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Author : David Chapman
language : en
Publisher: CRC Press
Release Date : 2017-11-27
Introduction To Tunnel Construction written by David Chapman and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017-11-27 with Technology & Engineering categories.
Tunnelling provides a robust solution to a variety of engineering challenges. It is a complex process, which requires a firm understanding of the ground conditions as well as the importance of ground-structure interaction. This book covers the full range of areas related to tunnel construction required to embark upon a career in tunnelling. It also includes a number of case studies related to real tunnel projects, to demonstrate how the theory applies in practice. New features of this second edition include: the introduction of a case study related to Crossrail’s project in London, focussing on the Whitechapel and Liverpool Street station tunnels and including considerations of building tunnels in a congested urban area; and further information on recent developments in tunnel boring machines, including further examples of all the different types of machine as well as multi-mode machines. The coverage includes: Both hard-rock and soft-ground conditions Site investigation, parameter selection, and design considerations Methods of improving the stability of the ground and lining techniques Descriptions of the various main tunnelling techniques Health and safety considerations Monitoring of tunnels during construction Description of the latest tunnel boring machines Case studies with real examples, including Crossrail’s project in London Clear, concise, and heavily illustrated, this is a vital text for final-year undergraduate and MSc students and an invaluable starting point for young professionals and novices in tunnelling.
Tunnel Lining Design Guide
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Author : British Tunnelling Society
language : en
Publisher: Thomas Telford
Release Date : 2004
Tunnel Lining Design Guide written by British Tunnelling Society and has been published by Thomas Telford this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with Technology & Engineering categories.
Of geotechnical and geophysical -- pr) operies 160 -- 10.3 4 Design of tunnel linings 1 61 -- 10.4 Instrumentation of the CTRL North Downs Tunnel 164 -- 10.5 References 165 -- Appendix I Abbreviations and symbols 166 -- Appendix 2 Risk management 168 -- A2l Introduction 168 -- A2.2 Scope 168 -- A23 Risk register 169 -- A21. 1 When to use the risk register 169 -- A2.32 Whalt is it? 169 -- A2.3.3 Assessment process 169 -- A2.3.4 Key steps 169 -- A2.3.5 Risk assessment, qualitative or -- quantitative? 171 -- A2.3.6 R anaingt risk 175 -- A2.4 References 17.