Research On Water And Soil Two Phase Flows Based On SPH Method

Large deformation problems such as landslide and dambreak,usually cause huge damage of person and property.It has great significance for designing projects and preventing disasters to simulate the large deformation problem accurately.Traditional numerical methods based on grids,is hard to simulate such strongly nonlinear problem.Smoothed particle hydrodynamics(SPH),a meshfree particle method based on Lagrange description,have inherent advantages in simulating the large deformation problems and multi-phase flow problems.The large deformation problems in water phase,soil phase and water and soil two phase are simulated by the code compiled by SPH in this paper.Specific work is as follows:(1)A water and soil two phase flow calculation code based SPH method is complied,and reliability of the code is verified by a lot of cases.The large deformation problems such as dambreak,landslide and landslide under water are simulated,and the influence of main parameters and techniques on the simulation results is analyzed.Besides,the program is parallelized based on OpenMp so that the computational efficiency are improved.(2)A novel boundary treatment approach for SPH method,i.e.the unified semi-analytical wall(USAW)boundary conditions,is improved.The concept of boundary particles without mass is proposed,which eliminates the interference of the mass of boundary particle to the problem domain and avoids the zero particle layer problem near boundary;two kinds of irregular particle distributions are proposed,which make USAW method more suitable for simulating complex boundary problems.(3)The improved USAW-SPH method is used to simulate the large deformation of the dam,and the problem of the pressure oscillations simulated at the boundary is solved.The problem of soil landslide is studied,where the physical properties such as cohesion and internal friction angle and the effects of numerical techniques such as artificial stress,massless boundary particle distribution on the simulation results,are analyzed.Besides,the motion law and pressure response of the wedge impacted by landslide are analyzed.At last,the two-phase model is used to simulate the landslide under water,where the influence of soil physical parameters such as hydraulic conductivity coefficient and dilatancy angle on the landslide under water is analyzed,and the change of velocity and pressure of water phase during landslide under water is studied.