Abstract
The huge tsunami induced by the 2011 off the Pacific coast of Tohoku Earthquake caused very serious damages to the port structures, particularly the coastal seawalls. Damage mechanism of breakwater has been studied in the past, and there are mainly three causes; (I.) horizontal force due to the water level difference between the front and rear part of breakwater, (II.) soil scour and erosion behind the seawall during overflow and (III.) piping destruction associated with the decline of the soil durability by seepage flow. In this study, an analysis method to represent (III.) piping destruction is developed. A Lagrangian particle method based on the incompressible Smoothed Particle Hydrodynamics (ISPH) is selected as the simulation tool for fluid dynamics of free surface flows and seepage flows, and the movement of soil after the piping destruction is modeled by the Distinct Element Method (DEM). A Darcy-Brinkman type governing equation is utilized for a fluid governing equation, and it is modified to apply a high porosity domain. ISPH method and DEM are coupled by utilizing an interaction force derived from a fluid governing equation. In a piping analysis, a macro-scopic empirical piping judgement is adopted to reduce an analysis cost. In this paper, the comparison between experiment and analysis for the seepage flow of a breakwater is conducted as a validation, and a piping destruction analysis is conducted.
