Wave Impact Pressures on Stepped Revetments

Nils Kerpen,Talia Schoonees,Torsten Schlurmann

doi:10.3390/jmse6040156

Nils Kerpen, Talia Schoonees + Show 1 more

Open Access

https://doi.org/10.3390/jmse6040156

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Abstract

The wave impacts on horizontal and vertical step fronts of stepped revetments is investigated by means of hydraulic model tests conducted with wave spectra in a wave flume. Wave impacts on revetments with relative step heights of 0.3 < Hm0/Sh < 3.5 and a constant slope of 1:2 are analyzed with respect to (1) the probability distribution of the impacts, (2) the time evolution of impacts including a classification of load cases, and (3) a special distribution of the position of the maximum impact. The validity of the approved log-normal probability distribution for the largest wave impacts is experimentally verified for stepped revetments. The wave impact properties for stepped revetments are compared with those of vertical seawalls, showing that their impact rising times are within the same range. The impact duration for stepped revetments is shorter and decreases with increasing step height. Maximum horizontal wave impact loads are about two times larger than the corresponding maximum vertical wave impact loads. Horizontal and vertical impact loads increase with a decreasing step height. Data are compared with findings from literature for stepped revetments and vertical walls. A prediction formula is provided to calculate the maximum horizontal wave impact at stepped revetments along its vertical axis.

Highlights

The increasing population living in coastal areas poses new demands in terms of the environmental and touristic compatibility of coastal protection structures
The general differences in the wave impact and wave run-up for a plain slope and stepped revetments with two different step ratios are given in Figure 3 for a better comparison and understanding of the results presented
Wave-induced impacts on stepped revetments have been investigated by means of physical model tests conducted in a wave flume

Summary

Introduction

The increasing population living in coastal areas poses new demands in terms of the environmental and touristic compatibility of coastal protection structures. The stepped surface of a stepped revetment induces additional turbulence in the flow, which leads to increased energy dissipation compared to smooth impermeable structures, traditional permeable structures provide more dissipation due to filtration and percolation effects [1,2]. References [2,4] highlight the reduction capabilities of stepped revetments for wave run-up and overtopping compared to smooth impermeable structures for regular and irregular waves. Reference [5] discusses the energy dissipation within the wave run-up at stepped revetments and detected similarities to steady flow conditions over stepped surfaces like spillways. The paper is structured as follows: First, the current understanding of wave impacts on stepped revetments is presented in Section 2 and key knowledge gaps outlined. The results are summed-up and contrasted in context of the present state-of-the-art and the advancement of knowledge outlined through this new study

Previous Studies on Wave Impacts on Stepped Revetments

Results and Discussion

Conclusions