Evaluation of Sediment Gradation Effects on Clear-Water Pier Scour with Densimetric Froude Number

Abstract

This study evaluates sediment gradation effects on clear-water scour at bridge piers. By considering the average erosion and deposition rates in a pier-scour hole, the normalized equilibrium scour depth is theoretically shown to be a cubic function of the densimetric Froude number. Comparisons with experimental data demonstrate that the cubic law achieves its best fit when the representative particle size is taken to be d84. The present prediction equation, which is founded on rational theoretical principles, provides an improved approach to evaluating sediment gradation effects on clear-water scour around bridge piers apart for pure empiricism.