Perforated caissons, which have the merits of lower reflection coefficient and smaller wave overtopping discharge and wave forces compared to traditional non-perforated caissons, are often used for building vertical coastal and harbor structures. As one of the most important hydraulic responses of coastal structures, wave overtopping must be carefully considered in engineering design. This study examines wave overtopping at perforated caissons for non-breaking waves. Based on experimental data, a modified predictive formula of the mean overtopping discharge for perforated caissons is proposed. The modified predictive formula is valid in a wide range of the relative crest freeboard. This study also demonstrates that the half value of the mean overtopping discharge for impermeable vertical walls predicted by EurOtop formula can be simply adopted as the mean overtopping discharge for perforated caissons with the same relative crest freeboard. The predictive methods proposed in this study should be valuable for engineering design of perforated caissons.
A Jarlan-type perforated caisson involving a perforated front wall, a solid rear wall and a wave-absorbing chamber between them has the merits of lower reflection coefficient and smaller overtopping discharge and wave forces in comparison with a traditional non-perforated caisson (Jarlan, 1961). Thus, perforated caissons have been often used for building vertical breakwaters, seawalls and quay walls. A variety of studies on wave interaction with perforated caissons have been carried out, and the relevant literature reviews have been given by Li et al. (2007), Suh (2009) and Huang et al. (2011). However, most of the studies focused on the reflection coefficient and wave forces on perforated caissons. Studies on wave overtopping at perforated caisson are still not enough.