Numerical methods are widely used to establish seismic fragility curves in the performance-based seismic design for buildings. However, non-linear dynamic analyses for large soil-structure systems are computationally demanding and alternative methods are sought to establish seismic fragility curves for buried structures. This paper proposes a simplified pushover method to calculate the non-linear response of underground structure. The pushover-based fragility analysis method can establish the conditional probability of the structure relevant to certain limits states by conducting a series of free-filed response analyses and one pushover static analysis. To verify the applicability of the method, two different subway stations designed for static loads only are used as examples for vulnerability assessment using the proposed method as well as the conventional incremental dynamic analysis (IDA) method. The structure capacity limits are associated with the inter-story drift ratio and the earthquake intensity measure is represented by the earthquake peak ground acceleration (PGA). The fragility curves predicted employing the pushover-based method are compared with those obtained from the IDA method. The comparison indicated that the probabilistic approach integrated with pushover-based strategies is an effective tool for rational and quantitative seismic fragility assessment of underground structures.

在建筑物性能化抗震设计中，数值方法被广泛用于建立地震易损性曲线。然而，大型土壤结构系统的非线性动力分析在计算上要求很高，并且寻求替代方法来建立埋地结构的地震易损性曲线。本文提出了一种简化的推覆法来计算地下结构的非线性响应。基于Pushover的易损性分析方法可以通过进行一系列自由场响应分析和一次Pushover静态分析来确定结构与某些极限状态相关的条件概率。为验证方法的适用性，两个不同的地铁站仅设计用于静态负载被用作使用所提出的方法以及传统的增量动态分析 (IDA) 方法进行脆弱性评估的示例。结构承载力限制与层间位移比相关，地震强度测量由地震峰值地面加速度 (PGA) 表示。将使用基于 Pushover 的方法预测的脆弱性曲线与从 IDA 方法获得的脆弱性曲线进行比较。比较表明，概率方法与基于 Pushover 的策略相结合是对地下结构进行合理和定量的地震易损性评估的有效工具。结构承载力限制与层间位移比相关，地震强度测量由地震峰值地面加速度 (PGA) 表示。将使用基于 Pushover 的方法预测的脆弱性曲线与从 IDA 方法获得的脆弱性曲线进行比较。比较表明，概率方法与基于 Pushover 的策略相结合是对地下结构进行合理和定量的地震易损性评估的有效工具。结构承载力限制与层间位移比相关，地震强度测量由地震峰值地面加速度 (PGA) 表示。将使用基于 Pushover 的方法预测的脆弱性曲线与从 IDA 方法获得的脆弱性曲线进行比较。比较表明，概率方法与基于 Pushover 的策略相结合是对地下结构进行合理和定量的地震易损性评估的有效工具。