Stability and Failure Mechanism of the Tunnel Face in Nonhomogeneous Clay with Longitudinal Slopes: A Kinematic Limit Analysis

Abstract

Longitudinal inclined tunnels are commonly encountered in practical projects, yet limited studies are available on determining the stability of the tunnel face with the presence of longitudinal slopes, especially in nonhomogeneous clay. This study employs the upper-bound finite-element method with rigid translatory moving elements (UB-RTME) to investigate the impact of longitudinal slopes on the stability of tunnel faces and their failure mechanisms. To enhance the computational performance of the UB-RTME, a series of mesh updating and refinement technologies is proposed. Furthermore, this study provides a comprehensive numerical implementation specifically designed for nonhomogeneous clay. By considering combined effects of slope inclination, tunnel burial depth, soil unit weight parameter, and undrained shear strength gradient, compact upper-bound solutions of the load factor