MUTIPHASE NUMERICAL SIMULATION ON LOCAL SCOUR AND PROTECTION BLOCKS DESTRUCTION BELOW GROUNDSILLS USING COUPLING METHOD OF E-MPS AND DEM

Abstract

 Riverbed degradation occurs in many rivers. It damages river crossing structures, such as weirs and groundsills, with backward facing steps. If a large flood occurs in such a situation, it is feared that the protection-blocks will be washed away due to local scour downstream from the structures. We conducted a vertical two-dimensional numerical simulation of local scour and the protection-blocks destruction occurring downstream from river crossing structures. These phenomena are complex phenomena due to the interaction between flow, sediment and rigid body. Therefore, a coupling method of the Explicit Moving Particle Simulation (E-MPS) method and the Discrete Element Method (DEM) has been developed. The E-MPS method is one of the MPS method. To investigate the applicability of the present method to local scour and the protection-blocks destruction occurring downstream from groundsills, we compared the numerical obtained by the coupling method with those from the movable-bed hydraulic model experiment we conducted. Although there is a problem in the reproducibility of changes over time, the results show that the present coupling method has the almost applicability to these phenomena.