Face stability analysis of a shield tunnel excavated along inclined strata

Abstract

The horizontally layered or even inclined strata are often encountered in practical shield tunneling. The influence of inclined strata on face stability of shield tunnels is not fully investigated by the existing studies. This paper adopts both theoretical analysis and numerical simulation to carry out research on face stability in inclined strata. The spatial discretization technique is adopted to construct a three-dimensional (3D) kinematic failure mechanism considering intersection between inclined soil interface and tunnel face. An analytical solution for critical support pressure is obtained. Besides, the critical support pressure and 3D kinematic mechanism are compared with numerical results to verify accuracy and effectiveness of analytical model. The influences of dip and position of inclined strata on face stability are thoroughly studied. The proposed failure mechanism can serve as a reference for face stability analysis in inclined strata.