CONFINED-CREST IMPACT: THE INFLUENCE OF THE TOE BERM ON THE IMPULSIVE LOAD CONDITIONS

Abstract

Composite vertical breakwaters are coastal structures used to defend port basins from waves in intermediate and deep water conditions. In order to safely use the inner side of harbors, it is important to limit wave overtopping. Parapet walls are used for this purpose. To improve the hydraulic efficiency of the parapet wall with a fixed crown wall height, the wall can be shaped giving rise to a recurved overhand toward the sea. Its function is to deflect back the incident waves. Recently, it has been shown that the interaction between non-breaking waves and recurved parapet can induce impulsive pressures due to the confinement of the incident wave crest deflected seaward by the overhanging structure. The new physical phenomenon has been called “Confined-Crest Impact (C-CI)” as shown by Castellino et al. 2018. This physical phenomenon can induce “unexpected” structural failure (Dermentzoglou et al., 2020). More recently, Castellino et al. (2021) extended the Goda’s formulae, which define the maximum pressures along a vertical breakwater, considering the “C-CI” induced by the presence of a recurved parapet. The conducted studies have concerned a vertical breakwater without any berm at the toe of the caisson. The purpose of this research is to extend this last work to a composite vertical breakwater based on a foundation berm.