Flume Experiment on the Sediment-Retaining Effect of Submerged Breakwaters under the Combined Action of Waves and Currents

Abstract

This research was initiated as design guidance for the extension works of a submerged trapezoidal riprap breakwater protecting the channel towards Huanghua Port in China. Based on flume experiments, the sediment-retaining effect of the breakwater was investigated in two sections under the combined action of currents and waves. We also discussed differences due to two kinds of facing layer—Accropodes and mold bag concrete. Three main observations are provided herein. First, the suspended sediments in front of breakwaters are mainly concentrated in the near-bottom 30% water depth scope and the interface can be seen clearly between the high concentration suspension and the upper clear water. Second, the sediment-retaining ratio of breakwater at −5.7 m isobath position is about 37%–49% and that at −7.3 m isobath position is about 61%–65%. Last, when there are wave breakings in the vicinity of submerged breakwater crest, the facing layers cause some differences of sediment-retaining performances.