Experimental Investigation on Destruction Mechanism of Coastal Dyke Due to Big Waves

Abstract

Hydraulic experiments and field data show that the destruction of coastal dykes is mainly caused by the suction from those foundations. I.e., repeated wave attacks erode and scour front sand beach, it follows that the shear resistance of the foundation decreases but the shear force produced by back flow increases. As a result, a significant amount of sand is sucked out from the foundation, leading to a dyke break. In this paper, new formulas of shear resistance and shear force are proposed with the analysis of some hydraulic experiments. An examination using those formulas clarifies whether or not the coastal dyke is broken by the suction. Moreover, the protection effect of the suction with the use of crushed stones for the dyke body is also confirmed by hydraulic experiment.