Abstract
In order to improve the stability of breakwater due to tsunami-induced overflow and seepage flow, it is effective that putting armor blocks on the harbor-side mound of breakwater. A hydraulic model experiment for the model of Kamaishi Bay breakwaters under tsunami condition was conducted to evaluate the extent of armor block damage focusing on the weight, the height ratio (the ratio of the armor block height to the armor block diameter) and the open ratio of the armor block (the ratio of the open volume to the armor block volume). As the result from this study, following conclusions were obtained. Although it was confirmed that the armor blocks slips downward due to seepage flow before occurring overflow, the armor blocks were stable against overflow. Although the damage of armor blocks with the weight of 0.29N was noticeable, the damage ratio was below 3.5% for armor block having the weight more than 0.29N. In the experimental conditions of this study, the damage of armor blocks with the triangle arrangement was smaller than that of the square arrangement. Stability ratio against surface slip was defined. This shows the tendency of damage of armor blocks.
