Damage Function of Rubble-Mound Breakwaters

The results of model experiments on rubble-mound breakwaters are presented. Emphasis was placed on the determination of the damage function for both perpendicular and oblique wave attack. The experiments were restricted to straight seaward slopes, 1:1.5,1:2, and 1:3 and angles of wave incidence 0○ (perpendicular attack), 30○, 45○, 60○, and 90○. No overtopping occurred. The diameter of the stones used in the tests was about 1 cm. From the results of the tests for perpendicular wave attack it followed that the shape of the damage curve varied with the breakwater slope. The tests for oblique wave attack indicated that it seems wise not to count on much reduction in stone weight, if any, for angles of wave incidence smaller than 45○. A comparison with previously published data on breakwater stability revealed a considerable scale effect due to the small stone sizes used in the model tests.