可液化粉土地层地铁车站结构地震响应分析

Seismic response of subway station structure in liquefiable silt layer

地震作用下地铁车站结构破坏一直是学术界广为关注的问题。受河流冲积和海水侵蚀等沉积环境影响,天津地区可液化粉土地层分布广泛,粉土液化会对地铁车站结构产生影响,但影响程度尚不清楚。目前,平行布置的地铁车站群作为典型交通枢纽,在城市建设中越来越普遍,车站群中临近双车站的抗震问题亟待研究。通过三轴试验研究黏粒含量对粉土静、动力特性的影响,基于塑性边界本构模型PM4Silt标定中不同黏粒含量粉土模型参数及基于有限差分分析,阐明低黏粒含量土层对地铁车站动力响应的不利影响,为可液化粉土地层车站选址提供建议;通过参数分析研究车站间距对临近车站相互作用的影响,揭示临近车站相互作用的影响范围,提供最优车站间距参考值。该研究可为临近车站设计提供理论依据。

The structural damage of subway stations under earthquakes has been a widespread issue.Affected by the sedimentary environment,such as river alluvium and seawater erosion,liquefiable silt layers are widely distributed in the Tianjin area.Silt liquefaction exerts an influence on subway station structure,but the degree of this influence is unclear.As standard transportation hubs,parallel subway station systems are becoming increasingly common in urban areas,and thus,the seismic problem of adjacent stations in a station group needs to be studied urgently.The influence of fine content on the static and dynamic characteristics of silt was studied with a triaxial test.The parameters of a silt model with varying fine content were calibrated using the bounding surface plastic constitutive model PM4Silt.Through finite difference analysis,the adverse effect of soil layer with low fine content on the dynamic response of a subway station was clarified.The results provided insights for the site selection of stations in a liquefiable silt layer.In addition,the influence of station spacing on the interaction between adjacent stations was studied through parametric analysis.The influence of the interactions between adjacent stations was revealed,and the reference value of optimal station spacing was provided.This study can provide a theoretical basis for the design of adjacent stations.