The objective of this study is to assess the maximum influence of wind on wave overtopping at rubble mound breakwaters with crest walls under oblique wave attack. Physical model experiments were conducted in which the maximum effect of wind was simulated by placing a rotating paddle wheel on top of the crest wall. This paddle wheel mechanically transported water onshore that would otherwise fall back into the sea after colliding with the crest wall. In this manner, the maximum influence of wind can be calculated as the ratio of the mean overtopping discharge measured during tests with the rotating paddle wheel deployed to the mean discharge measured during reference wave overtopping tests. An adaptation of the existing expression that predicts the maximum effect of wind on wave overtopping was proposed to account for oblique wave incidence. The maximum influence of wind was also assessed in terms of individual overtopping volumes. The analysis revealed that, similar to discharges, the influence of wind is greater for smaller volumes and gradually decreases for larger volumes. The wind influence factor can be applied directly to overtopping discharges measured in physical or numerical flumes to estimate the mean discharge under the maximum influence of wind, as the wind was not modelled directly. This approach yields the maximum influence of wind on wave overtopping making the scaling of wind no longer relevant. Lastly, overtopping rates for oblique wave attack were compared to existing empirical formulae used for design purposes.

Armoured slopes are commonly used in coastal structures to dissipate wave energy and protect adjacent infrastructure. To limit the height of these slopes in an efficient manner, regularly a concrete crest wall is placed at the upper part of the slope. Understanding the loads on these crest walls is essential for the design of coastal protection works. Conducting scaled physical model tests is a well established approach to confirm and optimise the design of coastal structures, albeit time consuming, scattered, and costly. This study aims to investigate the use of compact, focused wave signals in comparison to the common practice of using wave signals typically comprising a thousand waves in physical model tests. The physical model tests conducted in this study revealed that a compact wave signal was able to reproduce the extreme hydraulic response recorded during the simulation of a thousand irregular waves. This was observed in terms of sliding failure and extreme pressures exerted at the front vertical wall of the model crest wall. Results showed that the shape of the pressure signals, pressure distributions and integrated forces are reasonably well reproduced during focused waves. This suggests that this approach is promising for reproducing extreme responses at crest walls using focused waves; thus, resulting in reduced testing times. However, findings so far cannot support the use of this approach as a standalone tool for this application.