Numerical Simulation of Large Compression Deformation Disaster and Supporting Behavior of Deep Buried Soft Rock Tunnel with High In Situ Stress Based on CDEM

Abstract

Large compressive deformation of tunnels is a phenomenon involving plastic deformation and failure of surrounding rocks and often refers to the weak surrounding rock self-bearing capacity loss or partial loss. This research discusses the formation and evolution of large compressive deformation and effectiveness of the combined support of high in situ stress tunnel. From the new perspective of large deformation disaster caused by the structural failure of high in situ stress surrounding rock to clarify it, this paper illustrates the mechanism of progressive cracking and large deformation of high in situ stress soft rock tunnel from the aspects of the formation of self-bearing system, deformation evolution of the surrounding rock, mechanical properties of the surrounding rock, and failure characteristics. Accordingly, the continuous and discontinuous numerical simulation methods are used. The following conclusions are drawn by comparing the simulation results of surrounding rock under combined support with no support. (1) The supporting structure constitutes the self-supporting system with the surrounding rock and plays the roles of codeformation and load-bearing. (2) The support structure has evident reinforcing effect on the rock mass in the relaxation zone, thereby leading to the phenomenon of weakened rock mass failure. Moreover, the shear area develops to the compaction zone. (3) The supporting structure improves the bearing capacity of rock mass in the relaxation zone. It also increases the surrounding rock stress and reduces the range of the compaction zone. Simulation results verify that the combined support measures have a good suppression effect on the large compressive deformation, thereby providing a reference for similar projects and research on the large compressive deformation of soft rock.