Experimental study of scour characteristics and scour hole dimensions in consolidated silt sediment under a current

Abstract

Field observations show that silt is not always loose and that silt consolidation is common. In the study reported here, the characteristics of pile scour in consolidated silt (CS) under clear-water conditions were investigated and compared with those in loose silt. Experiments were performed to study the dimensions of equilibrium scour holes in CS, and the results show that the scour depth and radius in CS are smaller than those in loose silt, but the slope angle in CS is larger and the scour depth is inversely proportional to the dry density. It is found that the scour characteristics in CS differ from those in commonly used fine sand and silt, and most of the existing scour equations cannot predict the scour depth in CS. A mathematical relationship between the scour hole dimensions and the maximum scour depth applicable to CS is established, and a new equation is proposed for computing the maximum scour depth in CS with an error of less than 25%. The present work offers theoretical guidance for the design of scour prevention of piles and scour hole repair in CS.