Suitable Wave-Height Parameter for Characterizing Breakwater Stability

The description of a sea state just by its variance spectral density and duration is not enough to analyze the stability of rubble-mound breakwaters, since it does not include an adequate characterization of the large waves in that sea state. Numerical simulation has been used to demonstrate that different time domain characteristics result from the simulation of a sea state solely defined by its spectrum and its duration. As a result, it is also possible to obtain drastically different damage values on a given breakwater. A relationship between the groupiness factor and some extreme wave-height parameters such as H 1/20 has also been illustrated by this numerical simulation. Because of these results, arguments for the use of a new wave parameter, which is based on the distribution of large wave heights, to characterize breakwater stability are made. This new parameter also accounts for the duration of the test. The present paper may be helpful in explaining some of the variability found in the results of breakwater tests carried out by different laboratories.