Numerical simulation of scattering process of armour blocks on additional rubble mound behind breakwater during tsunami overflow using SPH method

摘要

In Japan, the concept of coastal structure design was drastically changed after the Great East Japan Earthquake. In the design of breakwaters, a "resilient" structure is required to prevent a breakwater from fall over damage due to scouring of rubble mound and seabed by tsunami overflows, by installing an additional rubble mound behind the breakwater. The particle method is useful for numerical simulation of large deformation problems treated in coastal engineering. DualSPHysics is an open-source fluid simulation code based on smoothed-particle hydrodynamics (SPH) method and is capable of dealing with a large number of particles because it can track the behavior of particles using GPUs. Few studies have simulated the movement of armour blocks behind a breakwater during tsunami overflow. This study conducts a numerical simulation to reproduce and clarify the scattering process of the armour blocks on the additional rubble mound behind a breakwater during tsunami overflow using DualSPHysics. The applicability of the numerical model is verified by comparing the performance of two types of armour blocks. The simulation model could reproduce the scattering process by using block data that considers the influence of boundary conditions. The performance diagram of the armour blocks was almost identical to the hydraulic experiment results, indicating the validity of the SPH model. The characteristics of the stability of the armour blocks against tsunami overflow could be clarified by analyzing the fluid force acting on the block.