地震作用下饱和软土场地地下结构动力参数敏感性模拟分析

Parametric sensitivity simulation analyses of subway station structure surrounded by saturated soft soil foundation under earthquake

为了研究饱和软土场地土性参数的变化对地下结构体系地震响应参数敏感性,基于u-p格式Biot动力固结方程和饱和两相介质有效应力动力求解方法,采用有限元开源程序平台OpenSEES建立饱和软土场地中地铁地下结构非线性动力相互作用体系有效应力全耦合模型并进行计算分析,其中土体采用多屈服面弹塑性本构,结构采用纤维截面弹塑性本构模拟,并由各土性因素参数(六因素、三水平)对饱和软土场地中地铁车站结构动力响应各指标进行极差、方差和线性回归分析的参数敏感性分析。结果表明:①密度和黏聚力动力响应评价指标最为敏感和影响显著;②渗透系数和孔隙率变化对动力响应评价指标敏感性和影响显著性最低;③在显著性水平为0.05情形下,动力评价指标和对应敏感性与影响显著的土性因素之间存在线性回归关系。

Based on the OpenSEES program,coupled numerical models of the interaction system of subway station structure embedded in saturated surrounding soil are developed by using the u-p formulations of Biot s theory to describe the saturated two-phase media.In this model,the multi-yield elastoplastic constitutive model is adopted for the soil,and the fiber section elastoplastic constitutive model is adopted for the structure.The analyses of range,variance,and linear regression of dynamic response index of the subway station structure embedded in soft soil sites are analyzed for parametric sensitivity with various soil factor parameters(six factors,three levels).The numerical results show that:(1)the density and cohesion are the most sensitive to the dynamic response evaluation index,and the influence is significant;(2)the permeability coefficient and the porosity are the lowest sensitivity to the dynamic responses evaluation index;(3)the sensitivity and impact of the change on the dynamic response evaluation index is the least;in the case of a significance level of 0.05,a linear regression relation exists between the dynamic evaluation index and the corresponding soil sensitivity.