考虑饱和土的地铁车站结构非线性地震反应研究

饱和土广泛存在于自然界之中，将土体视为固－液二相介质，基于biot饱和土介质动力方程的u-p形式研究了反映饱和土无约束域能量辐射效应影响的等效黏弹性人工边界单元，基于地震波转化为作用于人工边界节点上等效荷载的方法实现了波动输入。采用算例验证了等效人工单元的精度。建立饱和土-地铁车站非线性有限元整体模型，分析了考虑双相介质饱和土的波动传播，对比了饱和土及单相土在地震作用下地铁车站的地震反应，并与振动台试验结果进行了比较，研究表明：地震作用下采用考虑多孔介质的特性分析地基土与单相固体介质相比更加合理。通过对车站结构关键构件的加速度、位移和内力等进行分析，研究了饱和土－地下结构相互作用体系的地震反应。

Analysis of nonlinear seismic response of subway station considering saturated soil

The saturated soil exits widely on the earth. The soil should be considered as two phase medium of solid and fluid. The equivalent viscous-elastic artificial boundary element is studied regarding the effects of energy radiations of solid-fluid medium based on the u-p type of Biot equation of saturated soil. The wave input is realized by the equivalent load of earthquake on the node of artificial boundary. Its calculation precision is verified by comparison the examples. A nonlinear finite dynamic model of saturated soil-subway station is proposed for analyzing the wave propagation of soil in two phase medium and comparing with the seismic response in saturated soil and single phase soil under earthquake. The numerical results are compared with the results obtained from shaking table test. The results are shown that it is more reasonable to use the characteristics of multi-pore medium to analyze foundation soil under earthquake motion than to use the single phased medium. The seismic response of saturated soil and underground structural interaction system is studied through analyzing the acceleration, displacements and internal forces of the key elements in the station.