Influence of non-associated flow rule on face stability for tunnels in cohesive–frictional soils

This paper aims at analyzing the influence of non-associated flow rule on face instability of a circular tunnel in cohesive–frictional soils. A series of three-dimensional numerical simulations are performed to analyze the influence of dilatation angle on the limit support pressures and the failure zones. The dilatation angle significantly influences the limit support pressure and the failure zone. Then, a three-dimensional failure mechanism that consists of the ellipsoid and the multi-block is proposed based on the upper-bound theorem. Finally, the limit support pressures and failure zones obtained from the new mechanism are compared with those given by existing approaches of limit analyses, numerical simulation and centrifuge tests. The results indicate that the presented model is more effective in analyzing the face stability of tunnels. © 2021 Elsevier Ltd