大跨公铁两用斜拉桥塔区风环境

Wind environment around the tower of long span railway-highway combined cable-stayed bridge

摘要:

为研究公铁两用斜拉桥塔区复杂风环境，采用计算流体动力学(CFD)数值模拟方法对塔区公路桥面流场进行仿真分析，并结合大尺度桥塔-主梁刚性局部模型风洞试验，对公路桥面上3种典型车辆中心高度处和铁路桥面上列车中心高度处风速进行测量，引入风速系数λ、风速突变率ξ和风速波动率η，对比分析并讨论各空间位置处平均风速的变化和瞬时风速波动.结果表明：桥塔附近区域流场存在一定的风速加速效应；桥面不同高度处风速变化程度不一致，中型客车中心高度处流场突变更为剧烈；上风侧平均风速大于下风侧，但下风侧风速突变率更大；桥塔遮风效应对附近区域平均风速影响范围约为3倍塔柱迎风面尺寸宽度，在公路桥面上，对瞬时风速波动率的影响宽度略小于4倍塔柱迎风面尺寸，而铁路桥面上，对瞬时风速波动率的影响宽度略大于4倍塔柱迎风面尺寸.

Abstract:

To investigate the complex wind environment around the tower of long span railway-highway combined cable-stayed bridge, the computational fluid dynamics (CFD) was employed to simulate the wind field above the highway deck around the tower. Based on the wind tunnel test of large scale local rigid tower-girder model the wind speed measurements at the center height of three typical highway vehicles and train were conducted, respectively, and the wind speed coefficient λ, wind speed mutation rate ξ and the wind speed fluctuation rate η were introduced to analyze the average wind speed variation and the instantaneous wind speed fluctuation. Results showed that a certain wind speed acceleration effect was observed in the flow field near the tower. The degree of wind speed variation at different heights above the deck was different, and the change of flow at center height of the medium-sized coach was more intense. Wind speed at upwind side was greater than that at downwind side, but the wind speed gradient at downwind side was larger. Due to the wind shield effect of the tower, the influenced area of the average wind speed was about 3 times the width of the tower windward surface, and that of the instantaneous wind speed fluctuation was slightly less than 4 times the width of the tower windward surface on the highway deck, whereas it was slightly larger than 4 times the width of the tower windward surface on the railway deck.