基于SPH-DEM流-固耦合算法的滑坡涌浪模拟

Fluid-structure coupling algorithm based on SPH-DEM and application to simulate landslide surge

采用光滑粒子流体动力学(SPH)方法和离散单元法(DEM),并基于达西渗透试验原理,提出一种SPH-DEM耦合算法用于处理宏观尺度下离散体与流体之间的相互作用问题,并基于该流-固耦合方法采用FORTRAN语言建立滑坡涌浪数学模型。模拟了块体滑坡问题,并与试验数据进行对比以验证该耦合方法的有效性。模拟分析了离散体滑坡产生涌浪以及涌浪传播的过程,分析比较了数值模拟得到的最大涌浪高度与经验公式结果间的关系。研究表明:采用该耦合方法模拟水下块体滑坡问题得到的结果与试验数据吻合良好;模拟离散体滑坡涌浪问题时,较清晰地反映了滑坡体对水的排挤到涌浪的产生过程、水在滑坡体中的渗透过程和滑坡体与水耦合作用发生变形的过程;不同公式分析方法得到的最大涌浪高度之间均有一定差别,算例中滑坡体受重力作用沿倾斜坡面滑动入水过程更接近于潘家铮法的垂直运动模式,因此,模拟结果与之最为接近。

To handle the interactions between discrete medium and fluid in macro scale problems, the paper develops a fluid-structure coupling algorithm using smoothed particle hydrodynamics （SPH） method and discrete element method （DEM） and based on the principle of Darcy permeability test. A numerical model for landslide surge applying this coupling algorithm is developed by Fortran. The proposed procedure is used to simulate surge triggered by underwater block landslide, and numerical results are compared with the experimental data to verify the validity of the coupling algorithm. In addition, the generation, propagation and dissipation processes of surge induced by discrete medium landslide are also studied. Numerical maximum surge height is compared with the results of empirical formulas. Research shows that： simulated underwater block landslide surge is in good agreement with the tested results. In dealing with discrete medium landslide surge problems, the coupling algorithm can clearly reflect the process of surge formation, infiltration and deformation of landslide medium. Moreover the empirical formulas deduce different maximum surge heights. The process of discrete medium freely sliding along the inclined slope into water is closer to the vertical motion mode of Panjiazheng method, so does the numerical result.