Effect of connection modes on seismic responses of a diaphragm wall-subway station system subjected to mainshock-aftershock sequences

Abstract

Most existing seismic behavior analyses of underground structures simply consider a single earthquake. Meanwhile, the diaphragm wall, as an enclosure structure, is regarded as a security reserve and is always ignored in current studies. Herein, the characteristics of a diaphragm wall-subway station system with different connection modes under earthquake sequences were investigated using numerical simulation. The damage degree of the structural component was calculated through quantitative analysis of the tensile damage picture. The seismic damage level of the station structure was evaluated to characterize the damage transition effect induced by the aftershock according to the inter-story drift angle. Moreover, an empirical model for predicting the inter-story drift angle with respect to different peak accelerations was proposed. The research results indicate that the effect of the connection mode between the sidewall and the diaphragm wall on the damage evolution and deformation behavior of the station structure is significant. Compared with that of the compound wall structure, the seismic damage to the sidewall of the composite wall structure is much less severe, but the slabs become more vulnerable and suffer more severe damage. The accumulative damage triggered by aftershocks aggravates the extent of structural damage and even leads to damage transition. The conclusions illustrated in this paper contribute to a better understanding of the seismic resistance design of diaphragm wall-subway station systems under earthquake sequences.