临空液化场地中地铁车站侧移及上浮规律

Lateral displacement and uplift of the subway station near the free face in liquefiable soils

为研究双向地震作用下,液化场地中不同临空高度、地震强度、地铁车站埋深和车站至临空边的水平距离对地铁车站的影响,采用有限元-有限差分耦合数值方法,分析临空液化场地中车站结构的地震响应特征及规律。结果表明:临空场地的存在会引起地铁车站产生水平位移并发生转动,超孔隙水压力的累积和消散会使地铁车站先上浮再沉降;车站结构的水平位移、层间位移角和孔压消散后的沉降量随地震强度、临空高度的增加而增大,但随着车站与临空侧水平距离和地下结构埋深的增大而降低;临空场地会降低地铁车站在地震结束时刻的上浮量,降低程度随临空高度的增加而增加,但随着车站与临空侧水平距离的增加而减小;地下结构邻近临空侧的墙体内力小于非临空侧墙体,且内力差随临空高度的增加而增大;增大地铁车站的埋深、与临空侧的水平距离可以有效降低临空场地对地下结构产生的不利影响。

To study the effects of different heights of the free face,seismic intensity,subway station burial depth,and horizontal distance from the station to the free face on the subway station in liquefied soil under bidirectional earthquake action,the finite element-finite difference coupled numerical method was used to analyze the seismic response characteristics and laws of the station structure near the free face in liquefiable soils.The results showed that:the existence of the free facewould cause the horizontal displacement and rotation of the subway station,and the accumulation and dissipation of the excess pore water pressure would make the subway station float up first and then settle down;the horizontal displacement,inter-story displacement angle,and settlement after pore pressure dissipation of the structure gradually increased with the increase of seismic intensity and free face height but decreased with the increase of horizontal distance between the station and the free face and the buried depth of the structure;the existence of the free face would reduce the floating of the subway station at the end of the earthquake,and the degree of reduction increased with the increase of the free face height but decreased with the increase of the horizontal distance between the station and the free face;the internal force of the wall near the free face of the structure was smaller than that of the non-free side wall,and the internal force difference increased with the increase of the free face height;increasing the buried depth of the subway station and the horizontal distance from the free face could effectively reduce the adverse effects of the free face on the structure.