Seismic stability of an underground cavern in jointed rock mass based on the discrete fracture network

Abstract

In the construction of underground structures in high seismic intensity areas, it is inevitable that a fault fracture zone will pass through the construction site. Therefore, it is very important to evaluate and analyze the stability of the unstable block, which is cut by the fault and the dominant joint group. In this study, the discrete element method was used to simulate the seismic response of an underground powerhouse of a hydropower station near a high seismic zone. The discrete fracture network (DFN) model was introduced to simulate the joint group. Moreover, to optimize the number of joints and improve computational efficiency under dynamic conditions, the joints in the DFN with little influence on the stability of the cavity, were deleted by the algorithm, and a nonlinear time-history response analysis method was used for dynamic calculation. Based on the simulation results obtained, it was possible to classify the instability of the unstable block, and corresponding suggestions for construction were provided. Additionally, these results can be used as a reference for the seismic design of similar underground structures.