Seismic response and damage characteristics of subway stations in inclined liquefiable sites

In this study, a cyclic dynamic damage constitutive model (referred to as the Damage model) was developed within the finite difference software FLAC3D by incorporating the Mazars damage variable into the Drucker-Prager (D-P) constitutive model. Using this proposed model, a numerical model of a subway station in an inclined liquefiable site was established. Dynamic analyses were conducted under various working conditions, considering different earthquake intensities and ground inclinations, to investigate the damage distribution and evolution characteristics of the subway station. The results indicate that the damage value increases with increasing earthquake intensity and ground inclination, and damage is likely to occur at the connections between walls, slabs, and columns. In an inclined liquefiable site, the subway station experiences simultaneous uplift, sliding, and rotational deformation due to the horizontal movement of the liquefied soil layer and the action of earth pressure. When the peak ground acceleration is 0.3g and the surface inclination angles are 1°, 2°, and 3°, the inter-story drift ratios of the subway station are 1/294, 1/234, and 1/217, respectively. Furthermore, the damage value on the earth-facing side wall is significantly greater than that on the opposite side wall, indicating that the station structure is more prone to damage in inclined liquefiable sites than in horizontal liquefiable sites. The comparative analysis of the liquefaction zone distribution, deformation, and damage characteristics of the subway station provides a theoretical basis for the design and construction of subway stations in inclined liquefiable sites.