Numerical Simulation and Scheme Comparison of Shallow and Unsymmetrical Tunnel in Soft Rock

Abstract:

Stress-strain of surrounding rock is an important foundation for analyzing the stability of tunnel excavation. The mature tunnel mechanics is mainly to numerically simulate the tunnel excavation at the present. In this paper, with large finite element software ANSYS, stress-strain of surrounding rock of the saddle-shaped shallow tunnel excavation in soft rock of different depth, slope angle and covering layer thickness are calculated and analyzed, the laws are educed, the schemes is compared and the reasonable scheme is confirmed. The results show that: it is reasonable for 2 times of the tunnel depth as the judgment of deep or shallow unsymmetrical tunnel; it is reasonable to reduce the depth and covering layer thickness on the condition that surrounding rock is stable without wall spalling and roof caving. The laws of stress-strain of the surrounding rock internal wall in the tunnel excavation may provide reference to selection of the supporting structure parameter.