Wave loads on rubble mound breakwater crown walls in deep and shallow water wave conditions

The semi-empirical formulae by Pedersen (1996) for wave loads on vertical front faces of stiff crown walls are based on model tests with deep and intermediate water wave conditions. A new series of model tests performed at the same test facility as used by Pedersen has revealed that the formulae by Pedersen overpredict the loads in shallow water wave conditions. This paper presents a modification/expansion of the formulae to cover loads in both deep and shallow water wave conditions. The modification is based on a series of 162 physical model tests on typical rubble mound breakwaters with crown wall superstructures. The implementation of shallow water wave conditions in the formulae is done by modifying the term for wave run-up to be dependent on the incident wave height distribution. Moreover, the adjusted formulae provide more accurate estimates of the wave loads on free walls without front armour protection. Pressure transducers with very high eigen-frequencies were used in the present model tests as opposed to the transducers applied by Pedersen which in some cases seem to have been affected by dynamic amplifications.