Experimental Study on the Correlation Between Wave Overtopping and Reflection Over an Absorbing Revetment: Non-Breaking Wave Conditions

Abstract

This study performed a hydraulic model experiment to analyze the correlation between wave overtopping and reflection over an absorbing revetment in regular wave fields without wave breaking. Regular waves that last 1.2-2 s and 1.0-2.6 cm high were generated in a two-dimensional wave tank with a depth of 50 cm. With respect to the experimental conditions, an absorbing revetment with two layers of Tetrapods (TTPs) installed on a foundation mound of sand stone was considered. To calculate the reflection coefficient, the time waveform measured using the wave gauges was substituted into a two-point method to separate the incident and reflected waves, while the overtopping rate was directly measured in a separate overtopping tank. According to the experimental results, the water surface waveform in front of the revetment differed depending on the presence of wave overtopping. Under the overtopping condition, the water level in front of the revetment increased and then gradually decreased. Under the non-overtopping condition, the water level continuously increased and then quickly decreased. With respect to wave reflection, under the non-overtopping condition, the reflection coefficient increased as the surf similarity parameter increased. Under the overtopping condition, the distribution of the reflection coefficient was below a certain level and exhibited no clear trend. As the surf similarity parameter increased, the water level at the time of wave overtopping increased. In addition, the longer the duration of wave overtopping, the greater the overtopping rate was. According to the analysis of the correlation between wave overtopping and wave reflection within the same period, the reflection coefficient generally decreased as the overtopping rate increased. However, this phenomenon was not observed in any of the experimental results.