A caisson with a rear parapet is advantageous because the wave force acts on the caisson and the parapet having a time lag, so that the total wave force becomes smaller. However, the wave force acting on the parapet was not well investigated, especially the impact wave force was not clear when the caisson locates in the surf zone. We carried out hydraulic model experiments to investigate the characteristics of the impact wave force on the parapet.
The experiments showed that the shape of the wave at the front of caisson varies wave force widely and the water splashed from the edge of the caisson makes large force on the parapet. Though the observed wave force changed when the tests repeated, the largest wave pressure acting on the parapet was about 3ρgHmax and it acted evenly from top to bottom of the parapet.
