Numerical Simulation of Scour Around Breakwaters Due to Tsunami

Abstract

Imwon Port had suffered from great damage by the tsunami triggered by the Central East Sea Earthquake of May 26,1983 and the Southwest Hokkaido Sea Earthquake of July 12,1993. Also, Japan has suffered from great damage by East Japan Tsunami on March 11,2011. Breakwaters have been built in the surf zone to protect coastal areas. Breakwaters disperse tsunami energy to reduce structure damages. If there were no breakwaters, we had suffered from more damage by tsunami. So, we have to investigate scour depth around the breakwaters by tsunami. The scour depth around the breakwaters could be very important factor for the economic and safe design of the breakwaters. Also, behavior of scouring near the breakwaters is related to safe of coastal structures and human life. In this study, a numerical model consisted of a transoceanic propagation and an inundation model. Both models were discretized by the finite difference method. The propagation and inundation of the tsunami were simulated by a two-dimensional linear Boussinesq equations and nonlinear shallow-water equations. The shallow-water wave theory and boundary layer equations were used in theoretical development, which resulted in a mathematical model for the ultimate scour depth in front of a seawall. So, we can expect scour depth by calculation with velocity within boundary layer, breakwater slope angle and incident wave height.