地铁车站模型地震破坏连续-离散耦合模拟分析

Simulating analysis of seismic damage of subway station structure model using continuum- discrete element coupling method

基于北京地区典型地铁车站结构的大型振动台试验建立了有限差分-颗粒流离散元耦合模型,对车站结构模型的地震响应和破坏现象进行了模拟分析。在耦合计算模型中,土体采用连续模型,结构采用颗粒流离散元模型模拟,在FLAC边界节点处建立接触面,将FLAC在大应变模式计算的位移通过接触面传输给PFC;并将颗粒与接触面计算的相互作用力传输给FLAC,作为施加在各节点上的力,从而实现并行耦合运算。结果表明,模型的计算结果与试验结果拟合得较好;地震加载过程中,柱板、墙板节点为地铁车站模型结构的薄弱部位;模型的整个破坏过程和能量转化过程分为3个阶段进行;颗粒孔隙率、配位数和接触力的变化以及能量的转化规律能够反映结构的破坏过程。

Based on a large - scale shaking table test of typical subway station in Beijing Region, A continuum-dis- crete element coupled model was built to simulate the seismic responses and the damage process of subway station structure model. In the coupling model, the soil was simulated by continuaus model, and the structure was simula- ted by particle flow discrete model. Interfaces are built on the boundary nodes of FLAC and used as walls in PFC. Displacements calculated by FLAC in large - strain model were transfered to PFC through interfaces, and the inter- action force between particle and interfaces was transfer to FLAC as the force acted on nodes to realize the parallel coupling calculation. The results show that the calculated results are in good accordance with experimental ones. The nodes of column-plate and wall-plate are weak parts of subway station structure model during inputting earth- quake waves. The whole damage process and energy conversion process of structure model can be divided into three phases. The change of porosity, average number of contacts and contact force and the energy conversion law can re- flect the damage process of structure.