Barrier-Type Breakwaters: Transmission, Reflection and Forces

摘要

The study is on partly submerged breakwaters with a gap between the bottom of the breakwater and the sea bottom. Mainly fixed breakwaters, built up from the sea bottom with columns or piles, are treated. Floating breakwaters are also covered to some extent. The study consists of a theoretical and an experimental part. The calculated and measured main parameters are: reflected and transmitted waves, forces and moments, and pressure. In the theoretical study the structure/fluid interaction problem is solved by assuming a linear model and a non-viscous fluid. Three solution procedures have been developed; one for breakwaters with a rectangular cross section, a second for breakwaters with a rectangular cross section and a protruding bottom plate facing the incident waves and a third for breakwaters of more general cross section. The breakwaters are modelled to be impermeable. The experimental part deals mainly with a fixed breakwater with rectangular cross section. For regular wave excitations, transmitted and reflected waves, forces and moments, and pressure at the bottom of the breakwater were measured. It is shown how the wave protection can be significantly improved by using a breakwater with a protruding bottom plate rather than a rectangular one. This is confirmed both by potential theory and measurements.