Wave scour around a pile in sand, medium dense, and dense silt

This paper summarizes the results of an experimental investigation on wave scour around a circular pile in three kinds of soil, namely in dense silt (with a relative density of D-r=0.74), in medium dense silt (with D-r=0.38), and in sand (with D-r=0.23). The dense silt was achieved by wave liquefaction. Upon the completion of the liquefaction/compaction process, the pile was subjected to wave induced scour. The range of the Keulegan-Carpenter number (KC), tested in the experiments is from practically 0 to approximately 20. The Shields parameter in the experiments was such that the bed was live. The scour depth was increased by a factor of 1.6-2 when the bed soil was changed from medium dense silt or sand to dense silt. This is partly due to an increase in the angle of friction. The time scale of scour also was influenced by the density of the soil. The time scale was largest for the dense silt case, and smallest for the sand case in the experiments.