No abstract

The horizontal wave pressure on the front wall of the caisson protected by armor blocks on the rubble-mounted core is investigated by carrying out physical experiments. There have been few previous studies regarding this type of structure, and the characteristics of horizontal wave pressure on the structure are still unclear. Considering this, a series of experiments were performed by changing the configuration of the coverage rate in front of the caisson and the shoulder width of the armor blocks. For each of the different configurations of the model setup, wave pressure on the caisson was measured under 20 regular waves of different wave periods and heights. By analyzing the obtained experimental data, it was possible to quantify the effects of the coverage rate and the shoulder width on the wave pressure. The wave pressure tended to increase up to maximally 1.5 to 2 times at the exposed part of the caisson if it was incompletely protected. In addition, the wave pressure at the top part of the caisson was substantially reduced with the increase of the shoulder width of the armor layer. Based on these results, adjustment factors for evaluating such effects have been suggested, which can be applicable for the practical design of the caisson covered with armor blocks on the rubble-mounted core.

A series of physical experiments were carried out to investigate the characteristics of the horizontal active earth pressure exerted by rubble stones placed in front of horizontally composite breakwaters. Typically, the shoulder width of rubble mounds is shorter than the failure wedge assumed by Rankine’s earth pressure theory; therefore, it is not appropriate to apply the theory for the estimation of the horizontal pressure of rubble stones on the caisson. Considering this, physical experiments were conducted to evaluate the horizontal earth pressure with rubble stones having different shoulder widths in front of the caisson. The experimental results showed that the horizontal pressure was considerably lower than that obtained by Rankine’s theory when the shoulder width was shorter than the failure wedge width. Even when the shoulder width was sufficiently large to apply the theory, the earth pressure was approximately 17% lower than the value calculated byRankine’s theory. Based on these analyses, an empirical equation is proposed that can estimate the earth pressure on the caisson for a wide range of shoulder widths of rubble mounds.