Seismic response of subway station structures under straight-down near-fault

Given the deficiencies of knowledge on the seismic performance level of shallow-buried subway station structures in the near-fault site, the indirect boundary element method and the finite element method (IBE-FEM) integrated solution approach that considers the seismic response of the whole process of seismogenic fault-underground structures is proposed. First, based on the kinematic finite fault model, the IBE is used to solve the seismic wave field in the overlying soft soil site under the dislocation of straight-down strike-slip fault, and the feasibility of indirectly solving the seismic wave field by using the FEM is verified. On this basis, the influence laws of the fault-soft soil site coupling effects on the seismic performance of the subway station are preliminarily investigated by establishing a two-dimensional finite element model for the soil-diaphragm wall-underground structure nonlinear static dynamic coupling interaction system. The results show that in the near-fault region, the seismic damage of the subway station structures has typical hanging wall effects and concentration effects, and it's more likely to enter the stage of plastic deformation development. In the far-fault region, due to the fault-site coupling effects, the seismic wave field attenuation is slower in the footwall site, and the overall seismic damage of the station structures in the footwall is slightly larger than that in the hanging wall. This study may provide a new idea for the seismic response analysis of underground structures under near-fault site conditions, and it is of great significance for the seismic design of underground structures in the related site.