Water And Sediment Numerical Simulation Of The Influence Of Bridge Piers On River Course Evolution

River bridge construction project is increasing,and bridge pier in river water cross section area decreases,and change the channel,flow pattern and flow direction in flood season to quickly to the water downstream of human activities,resulted in river water and river channel of the river on both sides of the soaking and scour,impact on the river channel evolution and bank slope stability,etc,to inconvenience on both sides of the ecology and the life of people.Based on the full collection of mudanjiang section of flow,water level and flow sediment concentration etc,in view of the research of building Bridges affect river channel evolution of the actual problem,the first bridge pier is obtained by using the theoretical analysis of river flood line indicates the high value,and then based on MIKE21 study of containing branching river to carry on the numerical simulation of river channel evolution,under the mudanjiang five flood return period,The parameters are calibrated to study the influence of the hydrodynamic model of the bridge pier on the flow field,and the changes of the water level,the velocity,the split ratio and the main stream line are analyzed.The numerical model of sediment was established to simulate the influence of bridge piers on riverbed scouring and silting,and the scouring and silting status of riverbed near each bridge pier was analyzed,so as to obtain the specific location of hidden dangers and the degree of potential hazards,which could provide reference for the formulation of protection projects.The results show that the water level and velocity increase with the increase of the standard of flood return period,and the water level rise of each crossing section is different due to the same flood return period under the pier,and the Jiaxinzi Island in the river channel is submerged under the condition of a once-in-a-century flood.With the increase of flood return period,the influence range of piers on the flow velocity gradually extended to the upper reaches of the river,and the flow velocity near some piers increased significantly.Considering the erosion effect caused by the current on the piers,the piers at specific locations should be maintained and strengthened.The piers will increase the distributary value on the left side of Jiaxinzi Island,and then make the main channel shift to the left.Bridge piers will aggravate the scour depth of riverbed,so the design and buried depth of bridge piers should be improved according to the scour depth of riverbed near different bridge piers,so as to ensure the normal operation of river course and bridge.