跨海大桥不同类型下部结构波浪力特性

Wave Force Characteristics of Different Types of Substructures of Sea Bridges

为研究海洋环境中下部结构所受波浪力及最危险来波方向,本文以头门港跨海特大桥为背景,以低桩承台桥墩、通航孔桥墩和高桩承台桥墩三种下部结构缩尺模型为研究对象,基于物理模型试验和CFD(Computational Fluid Dynamics)数值模拟,研究波浪力作用下的跨海大桥下部结构受力性能。通过下部结构物理模型顺桥向、斜桥向、横桥向迎浪时的水平波浪力时间曲线,对比分析物理模型试验和数值模拟得到的波浪力,并进行桥上行车性能的研究。结果表明:三种下部结构最危险的来波方向均为顺桥向,且受桥墩尺寸与结构形式的影响,迎浪侧的结构尺寸越大,产生的波浪力越大;桥墩部分和桩基部分的波浪力由速度力控制,而承台部分的波浪力由惯性力控制,当下部结构受波浪作用时,各部位水平波浪力的峰值并不同时出现,但均是承台处率先达到峰值;跨海大桥下部结构中水平波浪力峰值最大的部位与波浪作用位置有关;波浪力过大会影响桥梁行车的舒适性。

To investigate the wave forces acting on the substructures of offshore environment and the most dangerous wave directions,this paper takes the Toumen Port Sea Great Bridge as the background and focuses on the scaled models of three different types of substructures,including low pile cap piers,navigable hole piers,and high pile cap piers.Based on physical model experiments and CFD(Computational Fluid Dynamics)numerical simulations,the mechanical performance of the substructures of sea bridge under wave loads was analyzed.The time curves of horizontal wave forces under longitudinal,oblique,and transverse wave conditions for the physical model were analyzed,and a comparison was made between the wave forces obtained from the physical model tests and numerical simulations.At the same time,research on the driving performance on the bridge was carried out.The results show that the most dangerous wave direction for all three types of substructures is in the longitudinal direction,and the wave forces generated are influenced by the size and structural form of the piers.The larger the dimensions of the windward side structures,the greater the wave forces generated.The wave forces acting on the pier section and the pile foundation are controlled by velocity forces,while the wave forces on the pile cap section are controlled by inertial forces.When the substructures are subjected to wave loads,the peak values of horizontal do not occur simultaneously at different locations,but all reach their peak values first at the pile cap.Furthermore,the highest peak horizontal wave force in the lower structure of sea bridge is related to the location of wave action,and excessive wave force can affect the comfort of bridge operation.