Seismic response and vulnerability of subway station underground structures are greatly influenced by kinematic soil-structure interaction, which is a function of soil properties and stiffness. Therefore, this paper investigates the influence of parameters associated with soil-to-structure relative stiffness (F) on the seismic fragility curves of underground structures. Incremental dynamic analysis method is conducted employing finite element analysis to establish the fragility curves of the station structure considering 44 earthquake records. The soil was simulated as a two-dimensional (2D) finite element domain and its nonlinear behavior is described employing the Davidenkov constitutive model. Appropriate plasticity models simulated the nonlinearity of concrete and reinforcing rebars. It was found that the failure probability of the structure decreases significantly as soil shear wave velocity increases, and the change of probability of structural failure was quantified for changes in shear wave velocity within the range 200 m/s to 600 m/s. It was also found that the failure probability of subway station in heterogeneous soil is significantly higher than that of a structure buried in homogeneous soil. On the other hand, the cross-section type of the structure has less influence on its seismic vulnerability. The seismic performance of the structure with higher F is relatively better, while there are special cases where some structures with high F that are more susceptible to failure under earthquake than structures with lower F. The findings can provide helpful guide for the performance-based seismic design of underground structures.

地铁站地下结构的地震响应和易损性在很大程度上受到土-结构运动学相互作用的影响，这是土特性和刚度的函数。因此，本文研究了与土-结构相对刚度（F）相关的参数对地下结构地震易损性曲线的影响。采用有限元分析的增量动力分析方法，建立了考虑44次地震记录的车站结构易损性曲线。土壤被模拟为二维 (2D) 有限元域，并使用 Davidenkov 本构模型描述了其非线性行为。适当的塑性模型模拟了混凝土和钢筋的非线性。研究发现，随着土体剪切波速度的增加，结构的破坏概率显着降低，并针对剪切波速度在200 m/s至600 m/s范围内的变化量化了结构破坏概率的变化。研究还发现，地铁车站在异质土壤中的失效概率明显高于埋在均质土壤中的结构。另一方面，结构截面类型对其地震易损性的影响较小。F高的结构抗震性能相对较好，但也有一些特殊情况，F高的结构比F低的结构更容易在地震作用下发生破坏。