【摘要】 为了将只适用于固体的离散颗粒–连续土体耦合方法应用至饱和土体,构建流体与离散颗粒–连续土体的耦合框架,此框架要求流体方程具有边界网格移动能力,并且流体方程分别与离散颗粒和连续土体耦合时具有统一的形式。然后建立新的流体方程组,此流体方程组基于任意拉格朗日–欧拉描述以实现流体边界网格移动控制,并且在离散颗粒和连续土体区域以不同方式提取的流固耦合力可以纳入统一的流体方程进行计算。为了保证流体微分方程有限元离散后的稳定性,基于特征线分离方法对建立的流体方程进行分离分步,然后基于标准伽辽金离散获得其有限元格式。最后通过模拟可液化场地中地下管线地震响应的离心机试验,表明引入流体方程后的离散颗粒–连续土体耦合方法可以有效描述离散颗粒与地下结构的非连续动力接触作用,同时有效降低离散元的模拟规模,并且可以兼顾地下结构移动时流体的边界移动问题。更多还原

【Abstract】 For the approach of coupled discrete-continuous solids for solid phase to be extended to saturated soil,a theoretical framework of coupling the fluid with the discrete-continuous solids was established. The unified dynamic equations for the fluid-phase were established based on the ALE(arbitrary Lagrangian Eulerian)description which controlled the moving boundaries and meshes conveniently. The interaction forces between the fluid and the solid derived in the discrete and continuous domains separately were incorporated in these fluid equations in a unified form. The dynamic equations of fluid were split based on the algorithm of splitting the characteristic curves to obtain the proper forms suitable for the application of the standard Galerkin discretization procedure. The proposed method was applied to simulate the underground structure buried in the liquefiable soil under seismic excitation. The results of the simulation demonstrated that the proposed method depicted effectivelythe non-continuous contacts between the particles and the underground structure,reduced the number of particles for simulation and considered the moving boundaries for fluid-phase caused by underground structure as well.更多还原