Upper Bound Stability Analysis of Shield Tunnel Face in Nonhomogeneous and Anisotropic Soils

Liang, Qiao; Yao, Cong; Xu, Jingshu

doi:10.1007/s40098-017-0224-z

Cited by 9 publications

(2 citation statements)

References 21 publications

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“…When there is not enough supporting pressure, the soil mass tends to move into the tunnel and collapse accidents may occur. For dry or saturated soils, the log-spiral failure mechanism can be employed to depict this failure of tunnel face [15,16], where the associated flow rule is satisfied on the slip surface. This mechanism is also applicable to face stability analysis in unsaturated soils, considering the fact that the degree of saturation has no impact on their internal friction angle [25].…”

Section: Log-spiral Failure Mechanism Of Shield Tunnel Facementioning

confidence: 99%

“…In view of deep rock tunnels, Zhang et al [15] constructed a log-spiral failure mechanism and performed the corresponding upper bound analysis where the Hoek-Brown failure criterion was employed. Based on the same failure mechanism, Liang et al [16] studied the stability of a shield tunnel face excavated in nonhomogeneous and anisotropic soils. Mollon et al [17,18] proposed a spatial discretization technique for generating the failure surface point by point, and the solutions of collapse pressure were significantly improved with the aid of the constructed failure mechanism.…”

Section: Introductionmentioning

confidence: 99%

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Upper Bound Analysis for Collapse Failure of Shield Tunnel Face Excavated in Unsaturated Soils Considering Steady Vertical Flow

Zhang

2019

Mathematical Problems in Engineering

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Natural soils are mostly in an unsaturated state and the corresponding mechanical properties differ significantly from a saturated one. In traditional stability analysis for a shield tunnel face, the soil mass is typically assumed to be dry or saturated for convenience of analysis. In this work, based on the upper bound theorem of classical plasticity theory and the log-spiral failure mechanism, face stability of the shield tunnel excavated in unsaturated soils under vertical steady flow is studied. The profile of shear strength is determined by virtues of the unified effective stress approach and the analytical solution of matric suction under unsaturated steady flow. On this basis, the analytical expression for the supporting pressure is deduced and the sequential quadratic programming is employed to search for the optimal upper bound solution. Through parametric analysis it is found the fitting parameters of SWCC and the groundwater level affect the supporting pressure notably. Besides, the relevant influence of vertical discharge is also significant when clayey soils are concerned.

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Section: Log-spiral Failure Mechanism Of Shield Tunnel Facementioning

confidence: 99%