不同几何形状纱网沙障输沙量风洞模拟实验研究

Wind Tunnel Modeling Test on Sediment Discharge of PE Yarn Net Sand Barrier with Different Geometrical Shapes

风蚀危害是影响流动沙丘造林成效的关键因素。我们在跟踪调查纱网沙障野外固沙造林良好成效的基础上,进行了不同几何形状纱网沙障输沙量风洞模拟实验研究。结果表明:不同几何形状及其开口方向的纱网沙障改变了地表风沙流结构,拦沙效果显著;当沙障开口朝背风方向时,输沙量随着距离地面高度增加而减少,而沙障开口朝迎风方向时,拦截地表风沙流效果较好,且输沙量随着距离地面高度增加而呈抛物线形变化规律,迎风半圆型沙障最大输沙量在距离地面26~28 cm高度,迎风月牙型沙障在距离地面20~22 cm高度,而未设置沙障最大输沙量在距离地面0~2 cm;在沙障迎风侧0.5H和背风侧0.5H^2H范围内均处于积沙状态,并且距离沙障越近积沙越厚,而在沙障迎风侧1.5H^2.5H范围则以风蚀状态为主,这种风蚀积沙变化为在纱网沙障背风侧3H范围内植树固沙造林提供了理论依据。

Wind erosion is a key factor to influence the effect of afforestation in moving sandy dune. On the basis ofinvestigating the good effect of sand - fixing afforestation with PE yam net sand barrier in the field, the wind tunnelmodeling test has been done. The results show that the PE yam net sand barrier with different geometrical shapesand opening directions can change the surface sand flow structure with outstanding effects. I f the opening directionof sand barrier is opposite to the wind, the sediment discharge reduces with the increase of distance from theground. If the opening direction of sand barrier opens towards the wind, the sediment discharge change in a parabo-la type with the increase of distance from the ground. The maximum sediment discharge of windward semi - circularsand barrier is at 26 ？28 cm from the ground. The maximum sediment discharge of windward crescent - shapedsand barrier is at 20 ？22 cm from the ground. The maximum sediment discharge of no sand barrier is at 0 ？2 cmfrom the ground. The range of 0？ 5H in windward side and 0？ 5H ？2H in backward side of sand barrier is in sandcollecting state. The accumulated sand gets thicker with the distance closed to the sand barrier. The range of 1.5H？2. 5H in windward side of sand barrier is in wind - erosion state. The change of wind erosion and sedimentarysand can provide the theoretical basis for sand fixing afforestation in the range of 3H in backward side of PE yamnet sand barrier.