Abstract
After the Tohoku earthquake in 2011, coastal dikes are required to be improved their tenacity against tsunami disaster. And it is reported that scours of coastal dikes caused by tsunami overflow were mainly occured at the toe of the slolpe. In this study, the fixed-bed hydraulic physical experiment and numerical simulation were conducted to understand the distribution of local pressure on a dike under tsunami overflow. Moreover, some countermeasures to improve the tenacity of dikes were proposed and examined in the experiments. It was comfirmed that the distribution of pressure on the dike changed at the top and the toe of the slope, and large negative pressure occured at the top of the slope. To reduce the negative pressure is considered to be an effective way for improvement of its tenacity, so that small weir type countermeasures were set on the top and the toe of the slope and tested in the experiment. The negative pressure at the top of the slope and the large velocity at the toe of the slope were significantly reduced by the suggested countermeasures. It is successfully confirmed from the experiment that suggested countermeasures can contribute to improve the tenacity of dikes. Moreover, the numerical simulation using OpenFOAM simulation code was conducted and showed good agreement with the experiment results.
