Study on the effect of burial depth on seismic response and seismic intensity measure of underground structures

Considering the complexity of the soil-structure dynamic interaction mechanism, underground structures are restrained and influenced by the surrounding soil in earthquakes, and their seismic damage under strong earthquakes is different from that of above-ground structures. The seismic response of underground structures is influenced by several coupling factors, including structural form, ground motion parameters, and soil properties, etc. In addition, the burial depth of the underground structure is also one of the critical parameters affecting its seismic response. In this study, the computational model of soil-structure dynamic interaction at different burial depths was established by using the finite element software ABAQUS with a single-story, double-span Daikai subway station as the prototype. The influence laws of different burial depth conditions on the seismic response characteristics such as inter-story drift ratio, internal force of critical sections, and seismic damage of subway stations are systematically studied. Meanwhile, this paper compares the correlation and applicability of PGA (peak ground acceleration), PSSRD (peak site soil relative displacement), and SSSRD (structural side soil relative displacement) with the seismic response of underground structures under different burial depths by applying the principle of vulnerability analysis. The results show that PGA and SSSRD are relatively better IMs (intensity measure) in shallowly buried structures, while the relative superiority of PSSRD gradually increases with increasing burial depth, and PSSRD is a more reasonable IM in deeply buried underground structures.