Front Wall and In-Chamber Impact Loads on a Breakwater-Integrated Oscillating Water Column

Abstract

This work aims to enhance the evidence base of extreme impact loads on the front (outer) wall and within the chamber of an oscillating water column (OWC) integrated into a vertical breakwater. Data are from large-scale physical model tests (at 1:9 scale) at the large wave channel (GWK). The paper shows that established prediction methods for nonimpulsive and impulsive wave loads for conventional vertical breakwaters can be applied to the front wall of OWC breakwaters. For the first time, impact loads within the OWC chamber have been quantified, on the rear in-chamber wall and on the chamber ceiling. These are found to reach magnitudes comparable to front wall wave impacts. Novel video records from within the OWC chamber provide new insight on water column behavior, including three different classifications identified as “single,” “successional,” and “water column” ceiling impacts. Conditions at risk of violent impacts within the chamber are also identified. These will be valuable in quantifying front (outside) design forces, in-chamber impacts, and in seeking to minimize in-chamber impacts occurrence, in construction and in operational phases.