SCOUR AROUND CIRCULAR BRIDGE PIERS AT HIGH FROUDE NUMBERS

The results of laboratory experiments on scour around circular piers in cohesionless bed material at high Froude numbers, F, up to 1.5 are presented. The scour depths in sediment transport regime (F is greater than F sub c) first slightly decreases and then increases with the increase in the Froude number. A formula to predict the scour depth at Froude numbers (F-F sub c) is equal to or greater than 0.15, is developed. The limitations of some of the existing predictors of local scour are discussed, and a new formula to predict the maximum clearwater scour is proposed. (FHWA)