In this paper, a physical experiment is conducted to investigate the wave overtopping flow thickness on the crest of slope breakwater and the generated secondary waves behind the slopping breakwater. The relationship between the relative overtopping flow thickness, secondary wave height transmission coefficient and non-dimensional mean wave overtopping rate or the relative crest level are proposed. The experimental results could provide reference to practical engineering design and validations for associated numerical model.
Breakwater is a kind of important sea defense to prevent the coastal area or harbor from hitting by tides and waves. Sloping breakwater is one of the most common structure types of all. If the design embankment top elevation is low, waves will cross over the crest top in a great deal and to generate wave overtopping flow, and wash or even destroy the crest, and then come into a series of new waves behind the breakwater in the harbor. The new waves, which are called "secondary waves", have lots of influence on the berthing stability of the ships. Lots of researches pointed out that the strength of wave overtopping can be measured by the wave overtopping discharge, and then has the direct influence on the overtopping flow on the crest and secondary waves. Schuttrumpf and Oumeraci (2005) divided the whole process of the waves over sea dikes into five domains: wave parameters at the toe of the sea dike, wave transformation on the seaward slope up to the breaking point, wave run-up and wave run-down on the seaward slope, wave overtopping on the dike crest, and wave overtopping on the landward slope. They studied the conditions of the wave overtopping in these five domains in detail and proposed the formulas about the thickness of wave flow and velocity.