2023 Volume 79 Issue 18 Article ID: 23-18132
Cavity collapse caused by internal erosion of backfilling sand has occurred frequently at the back sides of coastal structures such as seawalls and quaywalls worldwide. Sea sands used as the backfilling sand may contain a large number of fragment of shells and coral, and their particle shapes may differ significantly from that of silica sand, but there has not been sufficient investigation into the effect of sand particle shape on a series of processes of internal erosion, cavity formation and collapse. In this study, we focused on sea sand and silica sand with the same grain size distribution as the backfilling sand, and investigated in detail the processes of internal erosion, cavity formation and collapse under actions of waves, rainfalls and overtopping waves by conducting prototype-scale experiments. The results demonstrated that the difference in suction caused by the difference in the particle shapes of the backfilling sands had a strong effect on the series of processes of internal erosion, cavity formation and collapse.
