Wave Erosion of Cohesive and non-Cohesive Embankments: Laboratory Experiments

Abstract

Laboratory experiments were carried out in a wave tank to investigate wave induced beach profile evolution and scarp recession on cohesive and non-cohesive model embankments. The cohesive embankment was constructed using a natural soil mixture, and the noncohesive embankment was constructed using cylindrical shaped polyethylene terephthalate (PET) pellets of uniform size. A standardized packing procedure was used for both cohesive and non-cohesive embankments. The onshore face slope of the embankment was approximately 30 degrees. The morphological evolution of the embankment was monitored using water level sensors and a time-lapse camera. Waves quickly eroded the bank face near the free surface and formed a scarp. While an equilibrium profile was established relatively quickly and at a much steeper slope for the non-cohesive embankment, the cohesive embankment continued to erode for a much longer period. The scarp of the cohesive embankment retreated by a series of wave undercutting and slump failures. An empirical relationship between incident wave height and embankment erosion was established for the tested conditions. The measured beach profiles were compared with the developed analytical solution.