成贵铁路贵州鸭池河特大桥设计风速及其特性研究

Study of Design Wind Speed and Wind Properties Determination for Yachi River Bridge on the ChengduGuiyang Railway in Guizhou Province

成贵铁路贵州鸭池河特大桥主桥为主跨436 m的中承式钢桁-混凝土结合拱桥,桥址区山高谷深,气象条件复杂。为确定该桥的设计风速及其相关特性,采用计算流体动力学方法,建立桥址区地形风场计算模型,计算桥址区的风剖面特性、跨向分布特性和风攻角特性等,并根据风速相关性分析推算其设计风速。结果表明:受峡谷效应的影响,横桥向来风时风速放大因子最大,其为抗风设计的主要风向;在桥梁建筑高度范围内,桥址区风速沿横桥向风速剖面具有较好的指数规律,风剖面指数为0.15,与相关规范中山区C类地表的指数有明显的差别;桥面高度处地势平坦,可不考虑峡谷效应;确定该桥设计基准风速为25.3m/s。

The main bridge of Yachi River Bridge on the Chengdu-Guiyang Railway in Guizhou Province is a half-through steel truss-concrete composite arch bridge with a main span of 436 m. The bridge is located in the region with high mountains and deep valleys, and the meteorological condition there is very complex. To determine the design wind speed and the relevant wind proper-ties ,the method of computational fluid dynamics was used to establish the calculating model of the topographic wind field. The wind profile characteristics, wind distribution along the bridge axle and wind attack angle at the bridge site were calculated, and the design wind speed was analyzed and deduced according to the wind speed correlation. The results show that the wind speed amplifi-cation factor is the maximum when the wind comes transversely due to the valley effect, which is taken as the main wind direction in the wind-resistant design. Within the range of the bridge height, the wind profile of the wind along bridge width follows the exponential law. The wind pro-file exponent is 0. 15, which is quite different from the exponent of the grade C ground surface in mountainous area. The ground is flat at the height of the bridge deck and the valley effect can be ignored. The design reference wind speed of the bridge is 25. 3 m/s, which can provide reference for the determination of the design wind speed for the bridge of the same type.