Evaluation method for seismic resilience of underground structures and its verification

A subway station is a crucial part of a city's subway system, and its recovery following an earthquake can significantly impact the overall resilience of the entire system. However, the post-earthquake repair of underground subway stations is complex, time-consuming, and costly, and the existing seismic resilience evaluation methods based on superstructures cannot be directly applied to underground structures. Therefore, this study builds upon previous fragility research, introducing the economic loss correction factor λ_{L, i} under different seismic performance levels and the recovery time correction factor λ_t to account for the unique challenges of post-earthquake repair in underground stations. This approach enhances the resilience evaluation method for underground station structures, analyzing the influence of recovery functions and site classifications on their resilience. The results indicated that the revised resilience evaluation method, which accounts for the particularities of economic loss and recovery time, can accurately assess the resilience loss of underground station structures. The correction factor λ_t should be determined based on the structural form, specifically, λ_t = 1.7 for a one-story, two-span structure, and λ_t = 4.0 for a two-story, three-span structure. Resilience loss is highly dependent on site classification and recovery strategies, with stations located on harder sites exhibiting lower resilience loss. Additionally, stations employing a rapid recovery strategy (exponential recovery) demonstrate reduced resilience loss.