Abstract
This paper presents preliminary design guidelines for wave overtopping when circular-shaped roughness elements (ring-type revetment) are placed on the upper slope of a coastal revetment. Such a type of revetment was designed during the tendering phase of the Afsluitdijk reinforcement in 2017 as an innovative and highly effective way of reducing overtopping rates along coastal revetments. The design combines a relatively smooth lower slope (~1 in 2.5), wide storm berm (~1.5x wave height) and the roughened upper slope (~1 in 3) with a specific pattern of circular elements, resulting in a roughness comparable to that of a double layer rubble mound slope with an impermeable core. To effectively reduce overtopping rates, the circular elements require an average height of ~1/10 of the wave height and diameter of ~1/3 of the wave height, as well as a specific placement pattern (staggered pattern and spacing ~1/10 of the wave height).Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/EYxSI9ymYa4
Highlights
The Afsluitdijk is a dike along the Dutch Waddensea connecting the provinces of North-Holland and Friesland
The design philosophy was to separate the technical functions of the dike revetment: the wave impacts to be absorbed by the smooth lower slope, the wide storm berm to transform the wave and the hydraulic roughness and low non-protruding wave wall on the upper slope to tackle wave runup and reduce overtopping (Figure 3)
Remarks Measured Measured at wave gauge 3 Measured at wave gauge 3 Measured From drawings From drawings Computed using EurOtop section 5.4.6 From drawings From drawings From drawings Computed using EurOtop section 5.4.6 See preliminary design guidelines Computed using measurements and average slope from the EurOtop From drawings From drawings From drawings From drawings, 0.25*Ru2%,smooth below the still water line (EurOtop) Smooth berm Smooth lower slope
Summary
This paper presents preliminary design guidelines for wave overtopping when circular-shaped roughness elements (ringtype revetment) are placed on the upper slope of a coastal revetment. High and breaking design wave conditions (Hm0= 4.27 m, Tp = 7.7s, 4.5% steepness), strict overtopping requirements (
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