Experiments on Stability of Concrete Armor Units at Convex Corner Trunk

Abstract

The breakwater is one of the most important structures in coastal areas and the rubble mound breakwaters have been most widely designed and constructed. When designing the rubble mound structures, the determination of the stable weight of concrete armor units is the most significant and critical problems. The stable weight of concrete armor units could be calculated by Hudson or van der Meer formula. The breakwater is assumed to be straight and the waves are propagating normally to the structures when using this formula. The weight of concrete armor units at the round breakwater head should be protected by 1.3∼1.6 times of that at the trunk part because the coastal engineers think it to be vulnerable. Recently the damage of concrete armor units at the convex corner of breakwater trunk was reported several times in Korea. However, there were no any design standards for this area. In this study, three-dimensional hydraulic model tests were performed to investigate the stable weight of concrete armor unit at convex corner area. The tetrapod was used to the target concrete armor unit in the study. The stable weight is suggested by stability coefficient, Kd by using Hudson formula. From this study, the stable armor weight at the convex corner is similar with that at the round breakwater head and this means that about 1.4 times of weight for trunk area was needed at convex corner area.