Local parameter for armor weight estimation

Abstract

A new surf parameter called the 'wave action slope' is introduced to represent local wave conditions in shallow waters by employing local values of wave length or wave celerity and wave height. The use of wave theory on a flat bed of depth at the front of the breakwater might be considered far superior to the simple adoption of the deep water wave length for characterizing surfing waves at a shoaling depth. The wave action slope is formed by the product of the breakwater slope and the ratio of the celerity to the wave height. The optimum or minimum weight of the armor unit is related to the wave action slopes, which are employed for developing new empirical equations. Analyzing the laboratory data of van der Meer revealed that the armor weights are closely related to the wave action slope. By using the new surf parameter given with local parameter values, we suggest a simple but accurate equation to estimate the breakwater armor weight. Several empirical equations are applied to cases of failure experienced along the eastern coast of Korea. The values given by the Hudson equation are satisfactory for 26 of the 57 total failure cases. The number of satisfactory cases decreases by using recent empirical equations; of the 57 failure cases, the number of satisfactory cases yielded is 17 for the van der Meer/de Jong equation and 13 for the equation of the present study considering local parameters. The reduced number of satisfactory cases may indicate improvement of the new empirical equations over the Hudson equation.