Development of analysis method for evaluating stability of river dikes during earthquake and overflow by a particle method

地震引起的河堤破坏是一个涉及液化的大变形问题，而溢流引起的河堤破坏是一个渗流-侵蚀耦合问题。等效于无网格法的质点法是模拟这类大变形问题的有效方法。本文将质点法中的质点法扩展为一种多相耦合动力分析方法，用于非饱和河堤地震分析。此外，为了模拟河堤溢流过程中的侵蚀，采用Navier-Stokes方程作为河堤表面溢流的控制方程，并采用HSMAC （Highly Simplified MAC）方法对其进行求解。将HSMAC作为CFD（计算流体力学）和MPM作为CSD（计算流体力学）相结合，提出了一种新的CFD-CSD耦合分析方法。

Damage of river dikes caused by earthquakes is a large deformation problem involving liquefaction, while that caused by overflow is a seepage-erosion coupled problem. Particle methods which are equivalent to the mesh-free methods are effective for simulating these kinds of large deformation problems. In the present study, MPM (Material Point Method) that is one of the particle methods has been extended to a multi-phase coupled dynamic analysis method to analyse unsaturated river dikes during earthquake. In addition, in order to simulate erosion during overflow, the Navier-Stokes equation has been employed as the governing equation of the overflow along the surface of the river dikes, and then it has been solved by HSMAC (Highly Simplified MAC), in which a tractive force is calculated by a frictio law. Coupling HSMAC as a CFD (computational fluid dynamics) and MPM as a CSD (computational fluid dynamics), a CFD-CSD coupled analysis method has been newly developed.