山区Y形河口附近桥址区地形风特性数值模拟研究

Numerical Simulation of Wind Characteristics over Bridge Site Near Y-shaped River Junction in Mountainous Area

为研究在山区Y形河口影响下桥址区的桥梁风载特性,以山区峡谷大跨度悬索桥桥址区真实地形为工程背景,应用CFD(computational fluid dynamics)的方法,建立了桥址区复杂地形区域风场数值模型.通过36个工况的分组对比分析,探讨了山区Y形河口对主梁的平均风速、风攻角、风剖面以及风速放大系数在不同来流方向下的影响规律,并分析了河口处河道的导流与山体的绕流作用.研究结果表明:不同于普通深切峡谷地形风特性,在Y形河口影响下,桥址区附近的平均风速最大增幅达24 m/s,平均风攻角主要表现为负攻角,出现了最高达1.13的风速放大系数,且河道的导流及山体的绕流作用会导致主梁风速分布不均匀.

To study the wind field characteristics in bridge site under the influence of Y-shaped river junction in mountainous areas, a long-span suspension bridge built over a deep-cutting gorge near a Y- shaped river junction is regarded as a typical example and a numerical model for the wind field distribution of the bridge site with complex terrain is established by computation fluid dynamics （CFD） method. According to comparative analysis of 36 cases in different groups, the influence laws of Y- shaped river junction on the average wind velocity, wind attack angle, wind profile, and wind velocity amplification factor along the bridge deck in different flow directions are discussed, and the effect of river diversion and flow around mountains at the junction are analyzed. The results show that unlike the wind characteristics in ordinary deep gorges, influenced by Y-shaped river junction, the maximum increase in the average wind velocities is up to 24m/s, the wind attack angles are mainly negative, and a large velocity amplification factor up to 1.13 occurs. The effect of river diversion and flow around mountains at the junction can lead to a large wind velocity difference on beam.