A Numerical Investigation of Local Scour Around Different Shape of Bridge Piers and Its Reduction

Abstract

Around the world, local scour is one of the leading causes of bridge collapses and other hydraulic structure failures. The study demonstrates the scour depth and fluid dynamics of different shaped bridge piers, including cylindrical, square, diamond, hexagonal-sharp nose, hexagonal-vertical nose, airfoil, upstream facing airfoil, downstream facing airfoil, oblong, and rectangle piers through simulations. This study aims to discover the most efficient pier with the lowest scour depth. Tapered shape bridge piers and collar plates around the cylindrical pier are also discussed here to reduce the effect of local scouring. The FLOW-3D software has been used to solve the most challenging free surface flow problems using the Renormalized Group (RNG) k-ϵ turbulence model. Positioning a collar plate below the bed level will decrease scour depth, and using a combination of one collar plate under the bed level and one collar plate above the bed level will reduce the scour depth even more. According to the study, the tapered cylindrical pier has the lowest scour depth among the other bridge piers. The scour depth of the tapered cylindrical pier is 19.23% lower than the tapered hexagonal sharp nose pier. In comparison to a non-tapered cylindrical pier and a cylindrical pier with one collar plate under the bed level and one above the bed level, the scour depth of a tapered cylindrical pier is 33.96% and 9.48% less, respectively. As the piers are streamlined and sharply edged, the scour depth is higher for airfoil and diamond piers. The scour depth of diamond pier is 98% greater than the tapered cylindrical pier. The analysis also indicates that there is more scouring in the vicinity of the piers upstream than downstream.