地震作用下软土隧道的易损性分析

Seismic Fragility Analysis of Tunnels in Soft Soils

隧道结构地震易损性是指在不同强度地震作用下隧道结构发生各级破坏的概率,对隧道结构的地震易损性评估不仅能为隧道结构的抗震设计提供必要的指导,也能为隧道结构的未来震害情况提供必要预测。本文在国内外隧道结构地震易损性研究的基础上,建立有限元模型对上海软土地铁隧道进行动力时程分析,并采用一维等效线性方法考虑土层的非线性特性,以获取上海软土隧道的分析易损性曲线,并与文献的分析易损性曲线及美国生命线联盟(ALA)指南中的地下隧道经验易损性曲线进行对比,验证了得到的软土隧道易损性曲线的合理性以及本文软土隧道地震易损性分析流程的合理性。

Seismic fragility of tunnels is the probability that tunnel structure’s demand equals or exceeds a limit state under a seismic ground motion given a specified intensity.The assessment of tunnel’s seismic fragility can not only provide some necessary guidance for the seismic design of tunnel structure,but also be used for future damage prediction.Based on the study of seismic fragility of tunnel structures in China and abroad,dynamic time-history analyses of a metro tunnel in soft soil of Shanghai were carried out by using finite element software.The nonlinear characteristics of the soil profile are considered by one-dimensional equivalent linear method.The fragility curves of the tunnel model were obtained and compared with the current analytical fragility curves from a referrence and the empirical curves from American Lifelines Alliance to highlight that the analytical fragility curves obtained are reasonable,and that the process for developing fragility curves for tunnels in soft soil is reasonable.