基于FVM方法的弯道斜交桥洪水影响研究及河势分析

Research on Flood Impact and River Regime of Skew Bridges Crossing River Bend Based on FVM Method

基于有限体积法(FVM),结合二维非结构网格,以某跨河湾斜交桥为例,建立桥位上下游水动力数学模型。模拟分析了不同频率洪水下桥梁建设对上下游水位、流速及河势的影响。研究表明,由于桥墩的阻水作用,桥上游水位壅高,桥墩间流速增加,桥墩迎水面和背水面流速减小。由于拟建斜交桥桥墩和天然河道呈一定夹角,导致下游水位左岸壅高右岸下降,左岸流速和挟沙力较工程前有所增加,右岸减少,影响范围集中在桥位附近河段。桥位所在河段弯曲,桥梁建设对桥位下游河段凸岸(左岸)防淤和凹岸(右岸)防冲,能起到一定积极作用,研究成果可为弯道斜交桥的设计提供参考。

Based on finite volume method(FVM)and two-dimension unstructured grid,taking a skew bridge crossing the river bend as the research object,this paper builds a hydrodynamic model of the upstream and downstream of the bridge,and simulates and analyzes the impact of bridge construction on the upstream and downstream water level,flow velocity and river regime under different frequency floods.The results show that:Due to the water blocking action of the piers,the upstream water level of the bridge increases,the flow velocity between the piers increases,and the flow velocity of water face and back face of the piers decreases.As there is a angle between piers of the skew bridge and the natural river course,the water level on the left bank in the downstream rises and the right bank in the downstream drops.The flow velocity and sediment-carrying capacity on the left bank increases compared to those before the project,while those on the right bank decreases,and the affected area was concentrated in the river section near the bridge location.The river section where the bridge is located is bent.The bridge can play a positive role in preventing the siltation of convex bank(left bank)and the scour of concave bank(right bank)downstream the bridge.The research results can provide reference for the design of skew bridge.