THE USE OF PERFORATED PILE BEAKWATERS TO ATTENUATE WAVES

Abstract

A laboratory investigation was conducted to compare the transmission characteristics of one-row and two-row submerged perforated pile breakwater models. The laboratory tests were conducted in unidirectional waves with different wave conditions and pile porosity that varied from 0.0625 to 0.48. The influences of water depth, incident wave steepness and porosities were studied. From the experimental results obtained, it was found that when the number of rows tested was increased, more wave energy was dissipated. This resulted in the decrease in transmitted wave heights. When the pile porosity was increased, less wave energy was attenuated, resulting in higher wave transmission coefficient, Kt and the transmission coefficient, Kt decreases as the wave steepness increases for all porosity values. It was also found that lower water depth has a significant influence on the transmission coefficient at higher wave steepness with Kt being less than 0.45 at a water depth below 0.23 m for partially submerged condition compared to Kt being more than 0.50 at water depth above 0.35 m for the submerged condition, for both the one-row and two-row piles respectively.