Study on the Local Scouring of the Bridge with Sediment Control Dam

Abstract

Based on the characteristics of local piers scouring after built the sediment control dam in the downstream of the bridge, by the monomer model experiment of flume, sixty groups of local piers scouring experiments have been carried on.The principle and the influence factors of the local piers scouring have been analyzed. The results of series model experiments show that, with the sediment control dams, the local scouring of the piers, on one hand, is influenced by the approach velocity, down-shearing vortex, dimension of the piers, diameter and gradation of the bed sand; on the other hand, it is affected by the elevation of the dam and distance between the pier and the dam. Therefore, the concept of “control slope” is introduced in order to reflect the impacts of the sediment control dam to the piers. Based on the theoretical deduction and dimensional analysis, the equation, which is used to calculate the local scouring with no-uniform bed sand, is acquired by multivariate regression analysis, has been testified by the flume experiment and has got a good result. The optimum value of control slope and the equation of local piers scouring with that dam provide valuable references for bridge flood-control design of the shallow foundation with downstream sediment control dam.