不同外形粗糙元覆盖沙床面防风蚀效益的风洞模拟实验

In the hinterland of the Taklimakan Desert, it was found that there were Gravel-size Sand Cemented Bodies(SCB), and that the SCB had similar wind erosion benefits to the gravel-stone. The shapes of Gravel-size Sand Cemented Bodies were irregular. In order to study the inhibitory effect of the geometric shape of the sand surface roughness covering on the surface sand movement, this paper uses the spherical, triangular pyramid, cylindrical, square, pie and hemispherical six kinds of roughness（keep the single grain quality is equal), and choosethe coverage is 10% on the sand surface which is a emprical value that the influence each other is weak.Respectively, in the non-sand wind and sand wind conditions were carried out wind tunnel simulation experiments. Experimental results show:(1) Under the non-sand wind conditions,The wind erosion of the spherical, triangular pyramid, cylindrical and square roughness covering the bed surface is obviously smaller than that of the cake and hemispherical cover, square, and the anti-erosion efficiency of cylindrical, triangular and spherical is also better than pie and hemisphere. In the range of 1cm height (roughness height), the sediment transport capacity is in the order of CK> cake, hemispherical> spherical, cylindrical, triangular,square shapes. When the wind speed 10m/s, 0 ~ 5cm height capcity 90% of the sediment transport sand. With the increase of wind speed, the characteristic value of sand flow structure is easy to be eroded.(2) Under the conditions of sandstorm, the spherical, triangular prismatic and cylindrical covered sand surface is transformed from wind erosion to wind erosion with the increase of wind speed. The wind erosion increases with the increase of wind speed. When the wind speed is more than 10m/s, the sand bed surface showed a strong erosion, which cake shape and hemispherical ‘s sand barrier function is weak, which the wind erosion rate of the largest. On the 1cm height range, the sediment transport rate from large to small in order: CK> pie, hemispherical> spherical,cylindrical, square and triangular pyramid. Under each wind speed, 0 ~ 7cm height contains 90% of the sediment transport. When the wind speed is 8m / s, the surface roughness covering the bed surface exhibits an eutectic equilibrium state. With the increase of the wind speed, the bed surface is easy to be eroded.(3) There are also differences in the wind profiles of the bed with the different shpes element roughness. Within the height of the roughness, the wind speed decreases as the ratio of the roughness direction increases. In the case of spherical and square shapes with the same directional ratio, the chimeric effect of the square-shaped roughness is better than that of the spherical shape. When the height is greater than 7cm, the wind profiles is tend to be stable.(4) Whether it is non-sand wind, or sand wind conditions, the wind erosion are affected by the roughness’s direction of the ratio, height and spacing and other factors, on the conditions of the same coverage, fine high, with a clear boundary roughness’s protection benefits better than lower round roughness