复杂山区水库蓄水影响下的库区桥址风特性数值模拟研究

以某复杂深切峡谷大跨度悬索桥为工程背景,构建桥址区水库蓄水后的地形数值模型,对桥址区进行区域地形风场数值模拟研究.通过36个不同来流工况的对比分析,探讨水库蓄水后的主梁平均风速、风攻角、风剖面以及风速放大系数在不同来流风向下的变化规律.研究表明,山区库区桥址风场特性分布比较复杂:主梁横桥向平均风速随来流风向变化较大,主梁出现较大负攻角效应;典型工况下横桥向风速沿主梁由北岸向南岸递减;多数工况下,桥址区风剖面分布复杂,远不同于常规指数律;桥位出现较明显的峡谷风效应,风速放大系数最高达1.06.研究结果为水库库区大跨度桥梁的抗风设计提供一定的依据.

Numerical simulation of wind characteristics over bridge site in complicated mountains under the influence of reservoir water storage

To investigate the influence of mountain hydropower dam on wind characteristics for bridge site over reservoir area after water storage, a long-span suspension bridge over a deep-cutting gorge in complicated mountain area is regarded as an example. The numerical terrain model after reservoir water storage is built by Gambit and ICEM. Numerical simulation of the wind field distribution of the bridge site is carried out by employing CFD commercial software FLUENT. According to comparative analysis of 36 cases of different wind directions,the variation of average wind velocity,wind attack angel,wind profile,and wind velocity amplification factor along bridge deck in different flow directions are discussed. The result shows that the mountain wind characteristics over the reservoir area is very complex. Transverse average wind velocities of bridge deck change a lot in different flow directions, and a big negative attack angel is found on bridge deck. Transverse wind velocities decline along the bridge deck from north shore to the south shore in typical cases. Distribution of wind profile is complex in most cases,which is far different from the general exponential law. The bridge site has a relatively obvious acceleration effect with a wind velocity amplification factor up to 1.06. The research conclusions provide a basis for wind-resistant design of long-span mountain bridges over reservoir area.