土壤结皮面积与结皮分布对风蚀影响的风洞模拟研究

Wind Tunnel Study of Soil Crust Area and Distribution Affecting on Wind Erosion

土壤结皮在干旱半干旱地区广泛分布,是影响风蚀的重要因素。以准噶尔盆地东部矿区周边表层土壤为对象,通过控制土壤结皮率和结皮分布,利用风洞试验结合土壤风蚀传感器,对不同土壤结皮和风速条件下土壤风蚀量、风沙流结构、土壤颗粒释放的变化特征进行研究。结果表明:(1)风蚀量随风速增加显著上升,随土壤结皮率增加显著下降。均匀分布的结皮风蚀量整体低于集中分布的结皮;(2)跃移高度随风速增加而增加,高度在0~3 cm的收集物占总收集量的80%左右。14 m/s的风速能够使土壤发生跃移,而土壤结皮率达到50%能够有效抑制土壤颗粒跃移现象;(3)颗粒碰撞的数量与能量随风速的增加而增加,随结皮率增加而减少;首次出现颗粒碰撞时的风速随结皮率的增加而增加;颗粒碰撞的数量和能量在风速持续增加的时间段内增加至最大值,在风速稳定后开始下降,120 s左右降低至稳定值,随后不再发生明显起伏,在风速下降时间段内不发生颗粒碰撞。

Soil crust,which is an important factor affecting wind erosion,is widely distributed in arid and semi-arid regions.In this paper,taking the surface soils around the eastern mining area of the Junggar Basin as the object,wind tunnel test combined with soil wind erosion sensor were used to study the changes of soil wind erosion,sand flow structure and soil particle release under different soil crust and wind speed conditions by controlling soil crust cover rate and crust distribution.The results showed that:(1)Wind erosion increased significantly with the increase of wind speed and decreased significantly with the increase of soil crust cover rates.The wind erosion amount of uniform distribution was lower than that of centralized distribution.(2)The height of wind-sand flow increased with the increase of wind speed,and the collection at the height of 0~3 cm accounted for about 80%of the total.The wind speed of 14 m/s could make the soil saltation occur,and the soil skinning rate of 50%could effectively inhibit the saltation phenomenon of soil particles.(3)The number and energy of particle collision increased with the increase of wind speed and decreased with the increase of crust cover rates.The wind speed of the first particle collision increased with the increase of the crust cover rates;the number and energy of particle collision increased to the maximum value in the period when the wind speed continued to increase,and began to decrease after the wind speed was stable.It dropped to the stable value around 120 s,and then no obvious fluctuation occurred,and no particle collision occurred during the period when the wind speed was decreasing.