NUMERICAL ANALYSIS OF THE WAVE FORCE EXERTED BY THE TSUNAMI OVER THE SAND DUNE IN FRONT OF THE SEAWALL

Abstract

 During the Great East Japan Earthquake and Tsunami, radioactive substances leaked from the Fukushima nuclear power plant, causing loss of properties and serious environmental pollution. In order to prevent similar nuclear power plant accidents, it is necessary to consider tsunami damage under various conditions. The purpose of this study is to ascertain the influence of the presence of a sand dune in front of a seawall and the sediment transport on tsunami waves by conducting simulation analysis and comparing the results to hydraulic experiments, to provide data with a reference value to protect the nuclear power plant behind the seawall. In this study, based on the 2DH-3D hybrid tsunami behavior analysis model, an analysis model that can take into account the suspended load and bedload of the sediment, the tsunami density changes, and sand dune deformation has been developed. The validity of the numerical analysis is verified by comparing the results with hydraulic experiments. The results of this study indicate that 1) the developed analysis model appropriately reproduces the experimental results such as the wave force acting on the seawall; 2) under the circumstances of the long-period wave targeted in this study, it was discovered that the sediment transport did not have a large effect on the wave force; 3) the cause of 2) is presumed to be that the deformation of the sand dune is small when the tsunami reaches the seawall.