砾石覆盖对边界层风速梯度的影响  

Response of Wind Velocity Gradient at Boundary Layer to Gravel Coverage

作　　者：谭立海[1] 张伟民[1] 安志山[1] 李建国[1] 

机构地区：[1]中国科学院寒区旱区环境与工程研究所敦煌戈壁荒漠生态与环境研究站,甘肃兰州730000

出　　处：《中国沙漠》2012年第6期1522-1527,共6页Journal of Desert Research

基　　金：中国科学院知识创新工程重要方向项目(KZCX2-EW-313);国家自然科学基金项目(40671022)共同资助

摘　　要：通过莫高窟窟顶野外风洞实验对不同覆盖度砾石床面风速梯度的变化规律进行了研究。结果表明,床面砾石平均高度以下风速梯度随砾石覆盖度变化比较杂乱,而砾石平均高度以上风速梯度随覆盖度增加呈现出有规律的变化。从覆盖度5%到35%风速逐渐减小,40%～80%趋于稳定,35%最小。据此,大气边界层可明显分为两层,约以砾石平均高度为界,下层定义为粗糙亚层,上层定义为惯性亚层。粗糙亚层风速梯度随砾石间距高度比D/H值的变化同样比较杂乱;惯性亚层风速梯度随砾石间距高度比D/H值的变化规律比较一致:风速在D/H值0.3～1.5段趋于稳定,2.0～4.0段风速逐渐增大,1.5处风速最小。另外,对砾石床面不同高度阻风效应的计算表明,砾石床面的阻风作用在砾石床面表面附近最强(0.75 H～1.1 H),粗糙亚层阻风作用随高度增大而增大,惯性亚层阻风作用随高度增大逐渐减小。该粒径砾石阻风效应最优间距高度比D/H值为1.5,最优间距为3cm,最优覆盖度为35%,为砾石防沙工程的铺设提供了一定的参考作用。This paper simulated the variation of wind velocity gradient over gravel beds with different gravel coverages in a mobile wind tunnel over Mogao Grottoes,Dunhuang.Results revealed that the wind velocity gradient below the average gravel height changed with gravel coverage in disorder while the wind velocity gradient above the gravel height changed regularly with gravel coverage： wind velocity increased gradually from 5% to 35%,keeping steady from coverage 40% to 80%,and it was the lowest at gravel coverage of 35%.Therefore,the atmospheric boundary layer could be divided into two parts： the layer below the average gravel height was defined as the roughness sub-layer,and the one above the average gravel height the inertia sub-layer.In both sub-layers,the change of the wind velocity gradient with the ratio of gravel-to-gravel distance to the average gravel height（D/H） was similar with that with gravel coverage.In the inertia sub-layer,wind velocity was kept steady at D/H in 0.3-1.5,and increased gradually from 2.0 to 4.0,and it was the lowest at D/H at 1.5.Besides,according to the calculation of the wind-blocking effect,it was the strongest near gravel bed（0.75 H to 1.1 H）;in the roughness sub-layer,the wind-blocking effect increased with the increase of height;in the inertia sub-layer the situation was just the opposite.Furthermore,when D/H was 1.5 and D was 3 cm and gravel coverage was 35%,the gravel bed had the best wind-blocking effect,which had referential value for gravel-used sand-control project.

关 键 词：砾石覆盖度 砾石床面 风速梯度 阻风效应 野外风洞实验 

分 类 号：X169[环境科学与工程—环境科学]