干枯植被覆盖对公路沿线地表风沙流结构的影响

Effect of Dry Vegetation Cover on Surface Sand-carrying Wind Structure Along Highways

[目的]以内蒙古S105草原公路沿线地表为研究对象,探讨挟沙风作用下干枯植被覆盖度对风沙流结构的影响,旨在为防治公路两侧土壤风蚀提供理论参考依据。[方法]采用风洞模拟试验,在0%,20%,40%和50%覆盖度水平下测定输沙率。[结果]在挟沙风作用下,输沙率随干枯植被覆盖度的增大而递减,最大输沙率点的高度层不断上升。覆盖度为0%时,输沙率随高度的增加呈指数函数规律降低;覆盖度为20%,40%和50%时,输沙率随高度的增加呈递减→递增→递减→趋于平缓的变化规律;在85 mm高度以下符合多项式函数关系,85 mm高度以上符合指数函数关系。随覆盖度的增大总输沙量递减,最大抗风蚀效率达65.73%。[结论]干枯植被覆盖显著影响地表风沙流结构,可削弱挟沙风侵蚀力,是抑制公路沿线地表土壤风蚀沙化的有效措施。

[Objective]The influence of dry vegetation cover on the structure of wind-blown sand flow under the action of sand-carrying wind of S105 in Inner Mongolia Autonomous Region was studied in order to provide a theoretical reference for the prevention of soil wind erosion on both sides of a grassland highway.[Methods]Sediment transport rates were measured at 0%,20%,40%,and 50%vegetation cover levels by wind-tunnel simulation tests.[Results]Under the action of sand-carrying wind,the sediment transport rate decreased as dry vegetation cover increased,and the height of the maximum sediment transport rate rose as cover increased.When vegetation cover was 0%,the sediment transport rate decreased exponentially as height increased.As vegetation cover increased to 20%,40%,and 50%,the sediment transport rate decreased,then increased,then decreased,and then tended to be flat as height concurrently increased.These results can be described by a polynomial function below 85 mm height and by an exponential function above 85 mm height.Total sediment discharge decreased as vegetation coverage incrased,and the maximum anti-wind erosion efficiency was 65.73%.[Conclusion]Dry vegetation cover significantly affected the structure of surface wind-blown sand flow,which can weaken the erosion force of sand-carrying wind.Dry vegetation cover is an effective means of inhibiting wind erosion and desertification of surface soil along highways.