Abstract
Toe protection works for coastal dikes using concrete blocks have been proposed as one of the countermeasures to mitigate severe damage of the dikes foundation ground due to tsunami overflows. However, both mechanical stability of blocks and applicability of those engineering works are not fully clarified because it is generally difficult to investigate the hydrodynamics in such supercritical flows.
For this study, we examined the hydrodynamic forces exerted on a block of toe protection works on the foundation, using numerical simulations of tsunami flows over a model dike, which were conducted for four levels of tsunami height. Additionally, we performed laboratory experiments under the same hydraulic conditions as numerical simulations. Then, we investigated the validity of our numerical simulations, comparing outputs such as water depth, velocity, pressure, and hydrodynamic forces.
Results showed that the outputs of the numerical simulations are quantitatively consistent with those of the experiments, except for the lift force. This might be attributable to the installation condition of the target block against surrounding blocks of the protection work: a flat, regular, and even situation was not fully controlled for the block installation in experiments.
