日本阪神地震中大开地铁车站地震破坏机理分析

Earthquake Damage Mechanism Analysis of Dakai Metro Station by Kobe Earthquake

基于ABAQUS有限元软件,对日本神户大开地铁车站在阪神地震中的地震反应进行了数值模拟研究。采用能合理反映剪胀及应变软化特性的统一硬化本构模型来模拟土体的力学行为,同时应用塑性损伤模型描述了混凝土的力学特性,建立了大开地铁车站的三维数值计算模型。首先研究并对比了水平地震动单独作用,以及水平与竖向地震动共同作用下大开车站结构与围岩土体的地震反应,进而探讨了浅埋地下结构的地震破坏机理。数值结果表明:在强震作用下浅埋结构的上覆土体首先剪切破坏,进而丧失抗剪能力;上覆土体丧失抗剪能力后,在竖向地震作用下,其惯性力作用于车站结构顶板,该惯性力与侧壁土体引起剪切荷载的耦合作用使车站结构的中柱压剪破坏,继而结构顶板折断,最后结构整体倒塌。

Based on the ABAQUS software,the seismic responses of the Dakai metro station under the Kobe earthquake were simulated.The unified hardening model which can reasonably reflect the shear dilatation and strain softening characteristics was utilized to simulate the mechanical behavior of the soil,and plasticity damaged model was employed to describe the mechanical properties of concrete.The three-dimensional numerical model of the Dakai metro station was built.The seismic responses of the Dakai metro station and the surrounding soil were studied under the action of horizontal seismic input,and the combination action of horizontal and vertical seismic input,respectively.Moreover,the seismic damage mechanisms of shallow underground structures were explored.The results indicate that the shear failure occurs first on the overlying soil of shallow underground structures,and then the resisting shear capacity of the soil is lost.Besides,when the overlying soil layer lost its resisting shear capacity,the station structure was loaded with the inertia force of soil under the vertical seismic action.The result is that the middle column was damaged by the compress-shear force which was caused by the inertia force and the shear force from the nearby soil of the sidewall.And then the structure roof was broken,which led to the collapse of the station.