Result
Overall, the results of this research study have revealed for the first time the relative importance of the effect of the revetment porosity and slope steepness on the aforementioned processes involved in the interaction of irregular waves and porous revetments and their soil foundation, thus providing an improved understanding of both effects. More specifically, the most relevant findings of this study may be outlined as follows:
It was shown for the first time that an increasing porosity leads to a larger effect of the incident wave height on the reflection coefficient. A highly porous revetment behaves increasingly like an impermeable revetment with increasing wave heights and the porous structure becomes less effective in reducing wave reflection;
The effect of the revetment porosity on relative wave set-up hS/L0 is less pronounced than that of the slope steepness;
A larger porosity also results in lower values of both relative wave run-up and run-down with a more significant effect of the porosity on wave run-up;
Pressure damping performance Dp of porous revetments is more significantly affected by the revetment porosity than by the slope steepness. Dp increases with decreasing porosity over the entire range of tested surf similarity parameters xm-1,0.
The spatial development of the internal mean water level in the sand core beneath bonded porous revetments, which is crucial for the structure stability, is investigated systematically for the first time considering irregular waves. It is particularly shown that the internal wave set-up hint near the shoreline at the sand core is less affected by the swash processes on a flatter slope (1:6) than on the steeper slope (1:3).
Empirical based equations were derived for all considered processes. As in the main tests only two porosities and two slope steepnesses were considered, the validity of the obtained formulae is cautiously limited to the tested or similar conditions.