SCOURING MECHANISM BEHIND SEAWALL FROM TSUNAMI OVERFLOW AND OPTIMUM CONDITIONS TO REDUCE TSUNAMI ENERGY WITH AN ARTIFICIAL TRENCH

Abstract

Some of coastal structures were collapsed owing to the local scouring by overflows after Tohoku tsunami. In order to understand the characteristics of the scouring behind seawalls due to tsunami, experimental studies and numerical simulation were carried out. The sour profiles formed behind a seawall could be classified into two types. The turbulent kinematic energy has effects on the development of the scour hole. The kinematic energy will decrease with an artificial trench behind a seawall. The rate of energy decay depended on the scale of trench not the shape.