Numerical Simulation Of The Flow Field In Bridge Area And Influence Of Bridge Construction On Navigation

With the development of economy and transportation, many bridges across the river and sea have been built. The bridge piers in the waterway disturb the natural flow. It will bring some effects on the flow and sediment and then it affects river bed evolution and channel stabilization. At the same time, complicated 3D flow will be produced around the bridge piers and it will generate unsafe navigation influence area. Hence, it is significant to study the influence of bridge construction on the flow and navigation in bridge area for bridge design and navigation safety.Numerical simulation of the flow in the estuary of Yangtze River is carried out to analyze the influence of bridge construction on the navigation in the bridge area and navigation influence width is studied by taking the flow velocity and flow direction into account. Firstly, a 2D finite element mathematical model is established for the flow by using the Telemac-2D software. The model is verified by comparing the numerical results with the observation data of tidal level and flow velocity. Then a mathematical model of bridge piers is set up for the Sutong Bridge and numerical simulation is conducted. Based on the simulation results, the influence of bridge construction on navigation is analyzed by taking the flow velocity and flow direction into account. The conclusion has been drawn as follows.(1) The influence of piers on the flow is bidirectional: the water level in the downstream of bridge rises and that in the downstream lowers at flood tide; the regularity is opposite at ebb tide; the value decreases from bridge site to downstream and upstream.(2) The flow velocity of main piers increases and the value of the flow velocity also decreases from bridge site to downstream and upstream because of piers.(3) The angle between the flow direction and the normal direction of bridge axes enlarges and it is unfavorable for navigation safety.In the research of navigation influence width, ideal waterway and pier model are studied in order to simplify problem. The relationship of navigation width and the angle between the flow direction and the normal direction of bridge axes is summarized and the width is calculated and compared with others'results. The present study can provide a reference for choosing the bridge site and determining the navigable breadth of the waterway.