Scaling of Scour Depth at Bridge Pier Based on Characteristic Dimension of Large-Scale Vortex

Abstract

By examining the variations in the dimensions of a horseshoe vortex system in front of a pier, the present study proposes a new length scale, called pier hydraulic radius, for the scaling of the maximum scour depth at a bridge pier. It is shown that, in comparison with other length scales, the pier hydraulic radius is more effective for quantifying combined effects of pier width and flow depth on the local scour for both low and high flow conditions. A theoretical formula is finally derived, which agrees well with experimental data reported in the literature.