斜入射地震作用下地铁车站结构抗震性能分析

为了分析斜入射地震作用下地铁车站结构的抗震性能,以苏州地铁一号线星海广场车站双层地下结构为分析对象,建立了地震反应三维实体有限元模拟模型,模拟了斜入射地震作用下地下结构与围岩土体系统的三维地震反应,系统分析了大型地下结构地震反应的空间效应与永久变形规律. 结果表明:土体在地震作用下产生了不可恢复的塑性变形,主要为地表沉降,并显著受地震动入射角度的影响. 大型地下结构地震反应的空间效应显著,纵向地震反应表现为中柱较边柱强烈,永久变形大;横向地震反应表现为内侧柱较外侧柱强烈,永久变形大. 中柱是地下结构抗震最薄弱的部位,结构设计时建议中柱采用铰接,只承担竖向荷载,不承担水平剪力,将有利于提高地下结构的整体抗震性能.

Analysis of the Three-dimensional Seismic Performance of Underground

In order to analyze the seismic performance of the underground station structure under oblique incidence of ground motion, a 3-D finite element model of Xinghai subway station which is a double layer underground structure located in Suzhou was established. Based on the model, the seismic responses of soil and structure under different angles of incidence were researched. Then the space effect of underground structures ' seismic responses and the irrecoverable deformation were analyzed systematically. It is found that irrecoverable deformation generates in the soil subject to earthquake, which appears as the settlement of the ground surface. And the irrecoverable deformation is significantly affected by the incidence angle of ground motion. Moreover, significant space effect can be found in the seismic response of the underground structure, i. e. , the side columns have larger deformation in the longitudinal direction, whereas, the inner lateral columns have larger deformation than the outside lateral columns in the lateral direction. Furthermore, the middle-columns are the weak link due to the longitudinal discontinuity and lack of constraints of the surrounding soils. The articulated middle-columns are recommended in the design of underground structure, because such middle-columns only bear the vertical loading rather than the horizontal shear loading.