2025 Volume 81 Issue 17 Article ID: 25-17019
Large-scale scour can occur around the head of breakwaters when huge tsunami hits. Although previous studies have reported the instability of wave-dissipating block-covered breakwaters caused by such scouring and the possibility of the breakwater sliding due to such instability, effective countermeasures have not yet been established. In this study, the stability and scour prevention effects of armor blocks installed directly from the mound to the sandy bottom were verified through large-scale experiments in order to directly prevent scouring of the seabed and mound, which is the origin of damage. The results of the experiments using the high weight of the armor blocks revealed that the mechanism of damage is that the blocks are induced to slide in a plane toward the center of the scour hole that occurs in the uncovered area of the sandy substrate. The effective extent of block placement in relation to the scour hole in the uncovered area was also investigated.
