NUMERICAL SIMULATION STUDY OF HYDRODYNAMIC IMPACT OF SEA-CROSSING BRIDGE

Abstract

This paper used the Sea-Crossing Bridge in Quanzhou Bay as an example to simulate its tidal flow field after construction by a semi-implicit Lagrangian-Eulerian finite difference method. Triangle or quadrilateral meshes were used to refine a mesh for the sea area close to the bridge in the model. Each bridge pier was treated as land. The minimum side length of the mesh was approximately 5 meters. The simulation results showed that slow flow areas were formed in front of bridge piers due to the influence of rising and falling tides; at the back of bridge piers, slow flow areas were also formed after rising and falling tides passed the piers. The tide race direction of rise and fall in the main bridge area was basically perpendicular to the bridge site line. The influence domain of upstream and downstream flow along the bridge site line could extend approximately 1 km away. The variation of annual siltation intensity was mainly located in the water area around the bridge piers. The annual siltation intensity of suspended sediment around the main bridge pier increased about 2-20 cm/year. The annual siltation intensities between piers decreased about 1-2 cm/year. The movement of tidal flow and the variation of sediment back-siltation rule would have certain impacts on the marine ecosystem, regional flood control, and navigation in Quanzhou Bay.