复杂山区地形桥址区风特性的数值模拟

为了研究复杂山区地形桥址区风场空间特性变化规律，以位于我国西南山区的绿汁江大桥为工程背景，利用FLUENT对山区地形风场特性进行数值模拟，通过36个风向工况的计算分析，得到复杂山区地形桥址区风场的空间分布特性. 结果表明:受复杂地形影响，各桥位平均风速风剖面曲线和沿主梁横桥向风速曲线差异较大，桥址区附近地形最高点以上400 m风场仍明显受地形影响；受河道大角度弯曲影响，桥址区形成类似“单向开口槽”的地形，顺河流风向的来流风受山体阻挡，各桥位处的风速低于逆河流风向，两个风向的风速差值的平均值达13.6 m/s，且各桥位风攻角以负攻角为主；峡谷突宽使谷内风场出现一定的分流，突宽区风速稍有减弱，风场的分流量有限，使得在渡过突宽段后的峡谷缩窄区，风速依旧较大. 

Numerical Simulation of Wind Characteristics at Bridge Sites in Complex Mountainous Terrains

In order to investigate the variation of spatial characteristics of the wind field at bridge sites in complex terrains, a mountainous terrain was built in FLUENT to simulate wind field characteristics. The Lvzhi River Bridge located at a gorge area in the southwest of China was chosen as the engineering background, in which 36 cases with different wind directions were analyzed. Under the influence of the complex terrain, the profiles of average transverse wind velocities along the height direction and bridge axes are quite different. The complex terrain still has an impact on the wind field at 400 m above the peak of the terrain near the bridge site. Affected by large angle bending of the river, the bridge site area forms a terrain similar to the " one-way open slot”. The incoming wind along the river downstream direction is blocked by the mountain, so the wind speed at each bridge is lower than that in the river upstream direction. The average of the velocity differences between these two directions reaches 13.6 m/s. The wind attack angles of all bridges are mainly negative. The suddenly widened gorge results in a part of limited distributary of the wind field and the wind speeds decrease slightly in the widening area. After crossing the widened section, the gorge narrows and the wind speeds remain large.