Extension of shallow water rock armour stability formulae to nonlinear waves

The present paper presents new formulae for hydraulic stability of the main armour layer on rock armoured conventional rubble mound structures. In the present study, new stability tests were performed covering both mild (1:100) and steep (1:30) foreshores. The tests covered nonbreaking and breaking waves on the foreshore and also waves of very low steepness. The tests with the 1:30 foreshore showed the armour layer to be significantly more stable in the surging domain than predicted with the Van Gent et al. (2004) formulae. This was attributed to nonlinear waves with significantly larger H1/3 than Hm0. New stability formulae are presented and fitted to existing and present stability data. The new formulae provide a significant increase in the reliability for nonlinear waves compared to the Van Gent et al. (2004) formulae.