Study on deformation of layered rock tunnel based on material point method

The stability problems of layered rock mass are frequently encountered in tunnel and underground engineering. Affected by bedding plane, the mechanical properties of surrounding rock show obvious anisotropy, which makes its failure characteristics more complicated. Therefore, it is essential to clarify the deformation and damage characteristics of the tunnel in layered rock for the safe and efficient development. In this study, a numerical simulation tool based on material point method and strain softening model is used to establish the plane strain model of tunnel in layered rock, and the deformation process of the tunnel with different dip angles and different rock thickness is studied. The results show that: 1) Compared with the physical simulation test, it is proved that the tool used can simulate the complex process of tunnel deformation and instability, and effectively realize delamination, shear slip and rock fracture in the failure process of tunnel in layered rock; 2) The bedding plane has a significant influence on the failure characteristics of surrounding rock, and the damaged area increases significantly on the bedding plane, cracks are always concentrated in the direction perpendicular to the bedding plane, and the smaller the thickness of the rock layer, the larger the damage area of the surrounding rock; 3) With the increase of joint angle, the number of failure points presents a U-shaped trend, and the decrease of rock thickness will lead to an increase in the number of failure points and a decrease in the percentage of shear failure points.