Seismic fragility analysis can quantitatively evaluate the seismic performance of structures from a probabilistic viewpoint and accurately characterize the relationship between the degree of structural damage and ground motion intensity. This study investigates the seismic fragility of shield tunnels in three different liquefiable and non-liquefiable soils. A plane-strain finite element model of the saturated soil and shield tunnel is established via the OpenSees computational platform employing the multi-yield surface elastoplastic PressureDependMultiYield and PressureIndependMultiYield models to simulate the constitutive behaviour of liquefiable and non-liquefiable soils. The developed model is utilized to conduct nonlinear dynamic effective stress time history analyses to generate the seismic fragility curves and surfaces based on the incremental dynamic analysis method. Meanwhile, appropriate scalar- and vector-valued intensity measures are identified based on their correlation, efficiency, practicality and proficiency. Compared with the fragility curves based on scalar-valued intensity measures, the fragility surfaces based on the vector-valued intensity measures can better describe the effect of ground motion characteristics on the structural seismic demand, and thus can more accurately assess the structural seismic performance. The seismic damage probabilities derived from the fragility curves and surfaces reveal that the seismic damage risk of the shield tunnel in sandwiched liquefiable soil deposit is higher than that of the tunnel structure located in entirely liquefiable or non-liquefiable soil profiles. This finding underscores the importance of carefully evaluating the seismic safety of shield tunnels situated in sandwiched liquefiable soil deposits.

中文翻译：

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可液化土矿床中管片盾构隧道衬砌的标量和矢量值地震脆性评估


地震脆性分析可以从概率的角度定量评价结构的抗震性能，准确表征结构损伤程度与地震动强度之间的关系。本研究调查了三种不同的可液化和非液化土壤中盾构隧道的地震脆性。通过 OpenSees 计算平台建立了饱和土和盾构隧道的平面应变有限元模型，采用多产量表面弹塑性 PressureDependMultiYield 和 PressureIndependMultiYield 模型来模拟可液化和非液化土的本构行为。利用所开发的模型进行非线性动态有效应力时程分析，以基于增量动力分析方法生成地震脆性曲线和表面。同时，根据它们的相关性、效率、实用性和熟练程度确定适当的标量和向量值强度测量。与基于标量值强度测量的脆性曲线相比，基于向量值强度测量的脆性表面能更好地描述地震动特性对结构地震需求的影响，从而更准确地评估结构地震性能。从脆性曲线和表面得出的地震损伤概率表明，夹层液化土沉积物中盾构隧道的地震损伤风险高于位于完全可液化或不可液化土剖面中的隧道结构。这一发现强调了仔细评估位于夹层可液化土壤沉积物中的盾构隧道的抗震安全性的重要性。