Trunk and Head Damage on a Low-Crested Breakwater

Abstract

The spatial variation of damage on different sections of the trunk and head of a low-crested stone structure on a fixed bottom is examined using a cross-shore numerical model extended to oblique waves. The computed wave transmission coefficient and damage on the front slope, back slope, and total section of the trunk are compared with available data consisting of 188 tests. Similarity of trunk and head damage for a low-crested breakwater is proposed to predict damage on the front head and back head using the numerical model. The agreement is mostly within a factor of 2; however, the model overpredicts damage on the back head of a submerged structure. An experiment was conducted in a wave flume for a low-crested stone structure located inside the surf zone on a sand beach. The model is shown to reproduce the measured cross-shore wave transformation on the beach with and without the structure as well as the measured small damage on the structure. Sand deposition inside the porous structure will need to be accounted for in order to predict toe scour and accretion.