复杂群山环境下某桥址的风场特性

Wind field characteristics on a bridge site under complex mountain terrain

通过地貌模型风洞试验研究复杂群山情况下某桥址的风场特性,分析平均风速、风攻角、湍流强度、湍流积分尺度等随风向角和测点位置的变化特性,获得了复杂群山环境下典型位置测点脉动风速功率谱的变化情况。研究表明:复杂群山环境下,桥址的平均风速均小于梯度风高度的风速;爬坡效应使得顺山谷方向来流(顺风向,即风从谷口吹入)产生显著的正攻角,最大值为+35.3°;顺风向时,桥址各测点的纵向湍流强度和横向湍流强度达到最小,约为10%,其他风向下的湍流强度较大;顺风向时,桥址的湍流积分尺度较大,且随测点高度上升而增大,桥址各测点功率谱较来流功率谱发生明显变化,功率谱高频段能量显著增大、单峰特征降低。

In order to obtain wind field characteristics on a bridge site on a complex mountain terrain,small-scale topographic wind-tunnel model tests are employed.The variation characteristics of the mean wind speed,wind attack angle,turbulent intensity and turbulence integral scale with respect to the wind azimuth and measuring point position are analyzed.The changes of the wind speed spectrum of typical measuring points on the complex mountain terrain are also studied.The results show that the mean wind speeds of all the measuring points on the bridge site are less than that of the gradient height.When wind blows along the valley,significant positive attack angles are produced due to the wind climbing effect,with the maximum value reaching+35.3°.The along-wind and crosswind turbulent intensities in this wind direction reach their minimum values as low as nearly 10%,and become larger in other wind directions.The turbulence integral scale in this direction is much larger than that in other directions,and increases with the increasing height of the measuring point.The wind speed power spectrum in the direction has significant differences compared with the incoming wind speed spectrum,of which the energy in the high frequency section increases significantly and the feature of the single peak diminishes.