Abstract
The damage mechanism of armor blocks covering a coastal dike due to tsunami overflow is investigated using hydraulic experiments and numerical simulations using a three-dimensional coupled fluid-structure-sediment-seabed interaction model. From experimental results, it was found that there was a difference between the maximum scour depth during the overflow and the final scour depth after the tsunami subsided, suggesting that the maximum scour depth is essential in evaluating the stability of the coastal dike. Furthermore, it was demonstrated that the condition of tsunamis can affect the propagation of pore-water pressure to the lower surface of the blocks on the landward slope of the dike and thus the location of vulnerable blocks. From a comparison between experimental data and numerical results, the predictive capability of the model was demonstrated in terms of water surface elevations, final scour profiles, dynamic pressure on the upper surface of the blocks, and the location of vulnerable blocks and its time. This suggested that the model would be a useful tool in assessing this type of phenomenon.
