Author(s): Willi H. Hager; Jens Unger
Keywords: Bridge hydraulics; Bridge scour; End scour; Scour; Unsteady flow; Water flow
Abstract: Bridge pier scour was mainly investigated for steady approach flow conditions. This research considers the effect of a single-peaked flood wave on pier scour using both a computational and an experimental approach. Clear-water scour of incohesive sediment by an approach flow of well-defined flow depth and velocity, a circular-shaped cylindrical bridge pier and a flood hydrograph is investigated. The results relate to scour advance with time, generalized temporal scour development and the end scour depth in terms of the densimetric particle Froude number involving the maximum approach velocity and median sediment size. The effect of the remaining parameters on the end scour depth is discussed; predictions are essentially in agreement with model observations if the limitations for the present computational procedure are respected.