Numerical Simulation Study On Local Scour Of Bridge Pier Under Sand-laden Flow

Wading bridge construction changed the flow pattern,often cause bridge local scour,the threat to the bridge,the relative Yu Qingshui scour,carrying currents caused by the bridge pier local scour should have their own characteristics,the research is rare,for carrying water under the bridge pier local scour numerical simulation research has certain theoretical meaning and engineering practical value.This paper summarizes the relevant theories of sand-carrying water flow,discusses the local scour mechanism of bridge piers under the condition of sand-carrying water flow,and puts forward an improved empirical formula suitable for the local scour calculation of bridge piers under the sand-carrying water flow.FLOW-3D software was used to construct a numerical model of a rectangular straight single-pile river channel.RNG k-turbulence model and sediment movement model were used.Local compaction of the numerical model was carried out by nested grid method and FAVORTM discretization.Through numerical simulation,the local scour evolution rule of the bridge pier under the sand-carrying water flow is analyzed,and the influence of the upstream inflow velocity and the bulk density of the sand-carrying water flow on the local scour evolution of the bridge pier is discussed.The results show that the flow velocity around the pier increases with the increase of the upstream inflow velocity under the same sand-carrying water flow.At the same upstream inflow velocity,the flow velocity around the pier decreases with the increase of the bulk density of the sediment carrying water,and the flow velocity around the pier is the largest when compared with that of the sediment carrying water and clear water.The scour depth increases with the increase of upstream inflow velocity and decreases with the increase of bulk density of sediment carrying water.At the same upstream inflow velocity,compared with the sand-carrying flow and the fresh-water flushing depth,the upstream inflow velocity was the highest.At the same time,the paper makes a comparative analysis between the numerical simulation and the relevant experimental results,which shows that the numerical simulation analysis method and the conclusion are reasonable.