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通过野外调查及风场观测,研究了在主导风向为NW-SE时,榆靖高速公路K404处上风向植被防护体系的地面流场变化特征。结果表明:(1)风速和地形存在较好的相关性。在流动沙丘和固定沙丘迎风坡,风速放大率均为正,背风坡为负,背风坡没有产生回流,风速整体减小。风速放大率计算结果表明,愈接近地面风速的变化程度越大,风速放大率绝对值与垂直高度呈指数函数关系,风速放大率的大小与沙丘类型无关。(2)接近公路的贴地面风速显著下降,现有植被防护体系能够缓解流沙危害,植被的防风效果较好。(3)流动、半固定、固定沙丘的迎风坡地表风速廓线基本符合对数律,丘顶和背风坡风速廓线偏离对数曲线,固定沙丘粗糙度高于流动沙丘。
Through the field investigation and wind field observation, the change of ground flow field in the upwind vegetation protection system at Yujing Highway K404 was studied when the dominant wind direction was NW-SE. The results show that: (1) there is a good correlation between the wind speed and the terrain. In the mobile sand dunes and the fixed dune windward slope, the wind speed magnification is positive, the leeward slope is negative, the leeward slope does not produce backflow, and the overall wind speed decreases. Wind speed magnification calculation results show that the wind speed closer to the ground the greater the degree of change, the absolute value of the wind speed magnification and vertical height exponential function, wind speed magnification size and dune type has nothing to do. (2) The wind speed near the road to the ground is significantly reduced. The existing vegetation protection system can alleviate the risk of quicksand and the windbreak effect of vegetation is better. (3) The surface wind velocity profiles of the windward slopes in the fixed, semi-fixed and fixed sand dunes are logarithmically logarithmic, and the wind speed profiles on the hilltop and leeward deviate from the logarithmic curve. The roughness of the fixed sand dunes is higher than that of the flowing sand dunes.