Tunnel face stability under seepage flow conditions

Perazzelli, Paolo; Leone, Thomas; Anagnostou, Georg

doi:10.1016/j.tust.2014.03.001

Cited by 174 publications

(73 citation statements)

References 5 publications

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“… and Perazzelli et al . considered the seepage forces, so they adopted the submerged unit weight γ ′ in their calculations. In this work, because the effect of buoyancy forces is represented by pore water pressure, the saturated unit weight γ sat is used in calculation of the work rate of gravity.…”

Section: Numerical Results and Discussionmentioning

confidence: 99%

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The effect of pore water pressure on tunnel face stability

Pan

Dias

2016

Num Anal Meth Geomechanics

139

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Summary The kinematic approach in combination with numerical simulation is used to examine the effect of pore water pressure on tunnel face stability. Pore water pressure distribution obtained by numerical calculations using FLAC3D is used to interpolate the pore water pressure on a 3D rotational collapse mechanism. Comparisons are made to check the present approach against other solutions, showing that the present approach improves the existing upper bound solutions. Results obtained indicate that critical effective face pressure increases with water table elevation. Several normalized charts are also presented for quick evaluation of tunnel face stability. At the end of the paper, the influence of anisotropic permeability on tunnel face stability is also discussed, showing that the isotropic model leads to an overestimation of the necessary tunnel face pressure for anisotropic soils. Copyright © 2016 John Wiley & Sons, Ltd.

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Section: Numerical Results and Discussionmentioning

confidence: 99%

“…This is because the piezometric head in the working chamber at the tunnel face is lower than the hydrostatic head. This phenomenon can occur for earth pressure balance shield tunnels and for New Austrian Tunneling method tunnels . Both of these two phenomena lower the stability of the tunnel face.…”

Section: Introductionmentioning

confidence: 98%

The effect of pore water pressure on tunnel face stability

Pan

Dias

2016

Num Anal Meth Geomechanics

139

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“…So, the risk will also be accompanied by the entire construction cycle, which will affect all parties involved, and even those not directly involved, in such projects [4,5]. For tunnel engineering in complex geological areas, such as in the southwest mountainous region of China with high geostress, high water pressure, and karst features, such projects face serious geological disaster risk (e.g., from water inrush [6], collapse [7], rock burst [8], tunnel face instability [9,10], etc.) when tunnelling.…”

Section: Introductionmentioning

confidence: 99%

Entropy-Based Risk Control of Geological Disasters in Mountain Tunnels Under Uncertain Environments

Xia¹,

Xiong²,

Hao³

et al. 2018

Preprint

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Uncertainty is the main source of risk of geological hazards in tunnel engineering. Uncertainty information not only affects the accuracy of evaluation results, but also affects the reliability of decision-making schemes. Therefore, it is necessary to evaluate and control the impact of uncertainty on risk. In this study, the problems in existing entropy-hazard model such as inefficient decision-making and failure of decision-making are analysed, and an improved uncertainty evaluation and control process are proposed. Then the tolerance cost, the key factor in the decision-making model, is also discussed. It is considered that the amount of change in risk value (R 1 ) can better reflect the psychological behaviour of decision-makers. Thirdly, common attribute decision models, such as the expected utility-entropy model, are analysed, and then the viewpoint of different types of decision-making issues that require different decision methods is proposed. The well-known Allais paradox is explained by the proposed methods. Finally, the engineering application results show that the uncertainty control idea proposed here is accurate and effective. This research indicates a direction for further research into uncertainty, and risk control, issues affecting underground engineering works.

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“…Mollon et al [12] analyzed the limit support pressure of the face in a circular tunnel with a kinematical approach based on a three-dimensional multiblock failure mechanism. Perazzelli et al [13] numerically analyzed the stability of the tunnel face under seepage ow conditions with the so-called "method of slices," and the results indicated that the tensile failure of the wedge may be more critical than the shear failure if the gradient of the hydraulic head in the ground ahead of the face is high.…”

Section: Introductionmentioning

confidence: 99%

Effects of Water Inrush from Tunnel Excavation Face on the Deformation and Mechanical Performance of Shield Tunnel Segment Joints

Zhao

Wen

Yan

2017

Advances in Civil Engineering

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Water inrush from the excavation face often occurs in the current shield construction of metro tunnels. In this study, the discontinuity of shield tunnel lining and the interaction between the tunnel segments, the grouting layer, and the surrounding rock are considered. Based on the 3D nonlinear contact theory, a hybrid model of the shield tunnel is constructed. Considering the uid-solid coupling e ect of water and soil, the in uences of di erent water head di erences on the mechanical performance and deformation of segments and joints in the shield tunnel are studied. e water gushing from the excavation face leads to vertical convergence of the cross-sectional area of the shield tunnel, and joint opening and dislocation result in sharp decrease of the waterproof capacity of joints. Meanwhile, the stress in the vicinity of segment joints increases sharply, and local cracks occur in the segment lining. e axial force, shear force, and bending moment in the joint bolt are also signi cantly increased. Based on the current metro standard and the computational results in this study, an emergency control criterion is put forward by means of controlling the discharge of water: the water head di erence over the excavation face is required less than 4.6 M.

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Tunnel face stability under seepage flow conditions

Cited by 174 publications

References 5 publications

The effect of pore water pressure on tunnel face stability

The effect of pore water pressure on tunnel face stability

Entropy-Based Risk Control of Geological Disasters in Mountain Tunnels Under Uncertain Environments

Effects of Water Inrush from Tunnel Excavation Face on the Deformation and Mechanical Performance of Shield Tunnel Segment Joints

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