Seepage failure prediction of breakwater using an unresolved ISPH-DEM coupling method enriched with Terzaghi’s critical hydraulic gradient

Abstract This study develops a new numerical simulation model for rubble mound failure prediction caused by piping destruction under seepage flows. The has been pointed out as significant cause of breakwater during tsunamis. Once boiling and heaving occur on the surface, suddenly propagates in opposite direction flow. For prediction, coupled fluid-soil-structure simulator is developed combining ISPH fluid DEM mounds caisson blocks. ISPH, Lagrangian particle method incompressible fluids, can simulate violent flows such applied discrete rigid body simulations that include discontinuous deformation, large displacement block. ISPH-DEM coupling have already proposed technique multi-phase Still, cannot reproduce sudden onset from stable mound. Two simple assumptions are to reduce cost simulators structure composed Firstly, each modeled an idealized spherical with mean diameter rubble. size assumed be same particle. Under these assumptions, unresolved between particles fluid, which obtains interaction through empirical drag force, should applied. At time, block fully resolved spatial resolution size. Our contribution this paper how flow simulated DEM. original experiment using simulator. We identified conventional force models insufficient initiate observed experiment. It may due one part excessive averaging velocities coupling. Therefore, Terzaghi’s critical hydraulic gradient introduced heaving. Unstable particles, judged gradient, gradually lose their mass represent suspended fine particles. qualitatively sand backward erosion flow, shown