Abstract
Flap-gate breakwater is a coastal defense structure which lies down on seabed ordinally and rises up as a continuous seawall with its buoyancy under tsunami attack. Since The 2011 Tohoku Earthquake tsunamis caused serious damages of many coastal structures, it shoul be considered that the structures have to be resilient so as not to collapse immediately and completely against tsunamis exceeded over design levels. In this study, resistance properties of the flap-gate breakwater against tsunamis were examined through a series of hydraulic experiments using a flap-gate model which can measure reaction forces from a base mound and soil. As a result, it was confirmed that remarkable passivity resistance force acted on the flap-gate breakwater by burying its base body a certain depth in the mound, and the measured resistant forces can be estimated by simple calculation method.
