Abstract
Many breakwaters were damaged by the 2011 off Pacific Coast of Tohoku Earthquake Tsunami. Especially the breakwater tilted or moved due to scour at the rubble mound and a lack of bearing capacity. In the present study, DEM analyses for L shaped breakwater are performed in order to discuss the influence of scour on the lateral resistance. As a result, the scour behind the breakwater significantly influences the lateral resistance depending on the distance from the backside of breakwater, and the resistance becomes small with decreasing distance. The principle contact forces behind the breakwater develops at an angle of 25 degrees below horizontal line. Judging from this result, when the distance between the backside of breakwater and the scour is given as 2.3 times of the depth of embedment, the reduction of laeral resistance is slight and can be ignored.
