Abstract
One of the possible basic structural countermeasures taken for a breakwater to protect foundation mound and seabed against scouring caused by overflow is widening work for increasing the height of the foundation mound behind the breakwater. The widening work behind the caissons is topped with scour prevention work and a revetment to provide scour resistance to the structure. But the stability of armour blocks on the widening works is not cleared. In this report, the physical experiments were conducted to make clear the mechanism of failure of armour blocks under overflow of tsunami, and to consider the estimation methodology of stability of armour blocks. The results indicated that the stability of blocks related with the porosity of blocks and was estimated by using Isbash equations.
