Analytical Model for Response of Seabed beneath Composite Breakwater to Wave

The response of a breakwater and the underlying seabed in the presence of waves has been recognized as an important design problem in the field of harbor and coastal engineering. In this research, an analytical model is proposed for the response of a composite-type breakwater and seabed to sinusoidal standing waves. In the proposed analytical model, the problem of the response is decomposed into the wave mode, called a scattering problem, and the caisson motion mode, called a radiation problem. The analytical model is characterized by solving each decomposed problem using a complex Fourier series technique. It is verified, first, by comparison with an analytical solution of the simpler problem of a caisson on a seabed, and secondly, by comparing it with a finite-element solution for the response of a composite-type breakwater (caisson on a rubble mound base). In both cases, the comparisons are in good agreement for pore-water pressure. The proposed analytical model is superior to a numerical model in requiring far less computation time and revealing contributions to the overall physics.