Stability Analysis of Pressurized 3D Tunnel Face with Tensile Strength Cutoff

Abstract

The aim of this study is to propose an effective approach to evaluate the stability of a shield tunnel face with tensile strength cutoff by using the upper-bound limit analysis method. Based on the discretization and “point by point” techniques, two improved rotational failure mechanisms, namely the improved collapse failure mechanism and the improved blowout failure mechanism, are developed with the tensile cutoff for the first time. Based on these improved failure mechanisms, the critical collapse and blowout pressures of tunnel faces are then determined by using the upper-bound limit analysis method. The proposed method is then validated by comparisons with previous analytical solutions and numerical results, showing that the proposed method is an effective approach to evaluate the stability of shield tunnel faces. The influences of model parameters on the critical support pressures and the failure feature of the proposed mechanisms are finally presented.