Author(s): Tomihiro Iiboshi; Shoro Maeno; Keisuke Yoshida; Daisuke Takata
Linked Author(s): Keisuke Yoshida
Keywords: Surface Protuberance; Hydrodynamic force; Landward toe protection works
Abstract: Coastal dikes in Iwate, Miyagi, and Fukushima prefectures were severely damaged by tsunami overflow consequent to the 2011 off-the-Pacific-coast of Tohoku Earthquake. Based on this severe damage, the Tsunami Protection Committee in Japan recommended several methods for resilient structures for coastal dikes. Nevertheless, hydrodynamic forces acting on the landward toe protection works have not been sufficiently clarified. The hydrodynamic pressure of the dike slope and hydrodynamic forces of the landward toe protection works attributable to tsunami overflow were investigated experimentally in this study using coastal blocks of different types. Results show that uplift forces of the landward toe protection block do not increase proportionally with the tsunami height increase. Although surface protuberances of the blocks of the landward toe protection works increase the hydrodynamic force, they reduce the velocity related to scoring. In contrast, stepwise protection blocks decrease hydrodynamic forces and reduce the velocity over the landward toe protection works.