Toe Stability in Very Shallow Water Combined With Steep Sea Bottom

Abstract

It is common to construct a rock toe berm of three to four rocks wide when concrete armor units are placed in the armor layer. This toe berm is a relevant element, especially in very shallow waters combined with steep sea bottoms, where waves directly attack the toe berm and the lowest part of the armor. Several formulas are available to estimate the damage to rock toe berms. In this paper, these formulas are compared for different design conditions within their range of application. Most of these formulas use the damage parameter Nod. However, there are often situations in which wider toe berms are required for a safe design, and the damage parameter Nod is not recommended. A methodology is thus proposed to design wider toe berms based on the damage to the nominal toe berm of three rocks wide (Nod*), considered as the most shoreward part of the toe berm which effectively supports the armor layer.