Design Formulas for Block Revetments

Abstract

Design formulas for placed block revetments are evaluated. The various formulas, as published in literature, have a different background or are based on different experiments. Most formulas are based on an analytical solution of a ground-water flow equation for the flow in the filter layer and a schematized pressure distribution on the slope due to wave attack. Empirical formulas describing the wave pressure distribution as a function of wave height, wave steepness, and slope are presented. The pressure distribution used was based on experiments with regular waves. Recent experiments provide the opportunity to improve the wave pressure distribution, using the results of irregular waves. The resulting design formulas are described. These design formulas are based on laminar flow. The influence of turbulent flow is investigated. The formulas are used in a calculation example. It is shown that the permeabilities of cover layer and filter layer are very important for the maximum wave height the revetment can withstand.