乌珠穆沁沙地聚乳酸纤维沙袋沙障地表蚀积特征

Characteristics of Surface Erosion and Deposition of Sandbag Sand Barriers in Urumqi Sandy Land

沙障的蚀积特征对其发挥防护作用具有重要影响。为探究聚乳酸纤维(polylactic acid fiber,PLA)沙袋沙障对乌珠穆沁沙地沙化治理的效果,设置0.5 m×0.5 m、1.0 m×1.0 m、2.0 m×2.0 m和3.0 m×3.0 m共4种规格的聚乳酸纤维沙袋沙障,采用悬测法测量障格内部凹曲面形态,并分析不同规格沙障内部凹曲面的形态特征、蚀积效应。结果表明,沙障凹曲面中心风蚀深度随沙障规格的增大由5.17 cm增加到21.23 cm,而堆积强度随沙障规格的增大由3.86 g·cm^(-3)降至0.42 g·cm^(-3),障格内由堆积变为风蚀;蚀积系数稳定在1/9~1/8,随沙障规格的增大蚀积系数逐渐减小;障格内风蚀最深点随主风向偏移,障格内与主风向一致的方位风蚀量更大,剖面曲线开口更大;坡顶处凹曲面拟合效果大于坡中和坡底。综上所述,在乌珠穆沁沙地内,风蚀多发生在西北-东南和西-东方向上,且坡顶处形成的凹曲面较稳定,该地区适合布设2.0 m×2.0 m规格PLA沙障,研究结果为PLA沙障在乌珠穆沁沙地防沙工程中的合理应用提供了科学参考。

The erosion characteristics of sand barrier have important influence on its protective effect.In order to explore the effect of polylactic acid fiber(PLA)sandbag sand barriers on desertification control in Urumqi sandy land,four specifications of poly lactic acid fiber sandbag sand barriers were set with 0.5 m×0.5 m,1.0 m×1.0 m,2.0 m×2.0 m and 3.0 m×3.0 m.The concave surface shape inside the baffle was measured by suspension method.The morphological characteristics and erosion effect of concave surface in different specifications of sand barriers were analyzed.The results showed the wind erosion depth at the center of the concave surface of the sand barrier increaseed from 5.17 cm to 21.23 cm with the increase of the sand barrier specifications,and the stacking strength decreased from 3.86 g·cm^(-3) to 0.42 g·cm^(-3) with the increase of sand barrier size,which the accumulation turned to wind erosion in the barrier.The erosion coefficient was stable at 1/9~1/8,and decreased with the increase of sand barrier size.The deepest point of wind erosion in the barrier moved with the main wind direction.The wind erosion in the direction consistent with the main wind direction was greater,and the opening of the profile curve was larger.The concave surface fitting effect at the top of the slope was better than that at the middle and bottom of the slope.In summary,In Urumqi sandy land,wind erosion occurred mostly in northwest-southeast and west-east directions,the concave surface formed at the top of the slope was more stable,and the area should be suitable for laying 2.0 m×2.0 m PLA sand barriers.Above results could provide scientific reference for the rational application of PLA sand barriers in sand control project in Urumqi sandy land.