基于多相物质点法的土-水耦合动力模型

Soil-water coupling dynamic model based on multiphase material point method

作为无网格法的一种,物质点法(MPM)在计算中结合了有网格法和无网格法的优势,避免了有网格法在求解大变形问题时出现的网格畸变现象,近年来逐渐应用于大变形岩土工程问题和多相流问题中。基于标准物质点法的原理与算法,研究了多相物质点法的两种形式:适用于饱和土的两相单点格式;适用于非饱和土,考虑基质吸力的两相单点格式。为了验证多相物质点法模拟水力耦合多相流问题的准确性和适用性,模拟了Terzaghi一维固结问题、一维压缩波的传播问题和一维渗流问题3个土力学多相算例,并将所得到的数值解与理论解进行了对比分析。模拟结果表明,计算所得到的数值解与理论解基本保持一致,多相物质点法能够准确地描述饱和孔隙介质的水力特性和非饱和孔隙介质的渗流特性。最后,采用多相物质点法模拟了非饱和边坡降雨入渗问题,分析了边坡在降雨入渗作用下基质吸力的变化和大变形破坏全过程。

As a kind of meshless method,the material point method(MPM) combines the best features of the meshed method and meshless method in the calculation,and avoids the mesh distortion phenomenon of the meshed method in solving large deformation problems.In the last decades,MPM has been successfully applied in a number of large deformation geotechnical problems and multiphase flow problems.Based on the theory and algorithm of the standard material point method,two multiphase MPM formulations were studied:the two-phase single-point formulation for saturated soil,and the two-phase single-point formulation with suction for unsaturated soil.To examine the accuracy and applicability of the multiphase MPM when simulating coupled hydro-mechanical multiphase flow problems,Terzaghi’s one-dimensional consolidation problem,one-dimensional compression wave propagation problem and one-dimensional seepage problem were simulated and the results were compared to the analytical solution.The simulation results show that the numerical solution is generally consistent with the theoretical solution,and the multiphase MPM can accurately describe the hydraulic characteristics of saturated porous media and the seepage characteristics of unsaturated porous media.Finally,the multiphase MPM was used to simulate the problem of rainfall infiltration in unsaturated slope,and the change of matrix suction and the whole process of large deformation failure of the slope under rainfall infiltration were analyzed.