Mizutani Natsuki

 This study deals with the process that tsunami flow on land collides with a vertical wall. A tip of the tsunami flow collides with the wall and runs up along the wall and then the water column collapses on the following tsunami flow. In this study, the characteristics of the tsunami impact force on the wall caused by splashdown of the run-up water column were experimentally investigated. From the measurement of the pressure synchronized with the high speed video images, it was found that the local maximum values of the pressure were caused by splashing down of the water column. We assumed this phenomenon was casting up of the water column and then freely falling on the following flow. On the basis of this assumption, the elapsed time from the collision to the splashdown can be explained by using the maximum depth of the passing tsunami flow. The pressure distributions were not a static pressure profile when the local maximum pressure was caused by splashdown of the water column.