穿沙公路沙柳防护带平茬恢复期辅助沙障设置模式优选

Optimization of the sand barrier’s set mode during stumping convalescence of Salix psammophila protection belt on desert crossing highway

为防止穿沙公路路侧地表和路面在沙柳防护带平茬恢复期内被风蚀和沙埋,设置纱网沙障予以防护,并探究其发挥阻、输沙能力的最优设置模式。在沙柳防护带迎风侧,设置不同距离和角度的纱网沙障,对各模式下的风速和输沙率进行观测,计算粗糙度并分析。研究结果表明:设置距沙柳防护带不同距离的纱网沙障,风速流场等值线分布不同,其中距离为3倍障高时风速降低和恢复的速率较其他两个距离更快,且风速衰减幅度最大点所对应位置在沙柳防护带范围内;沙柳防护带内地表粗糙度均大于旷野(7.33倍以上),设置角以45°为最优;减少输沙率随纱网沙障设置角度的增加而减小,且均大于88.08%,距离为3倍障高时各角度减少输沙率均值为89.14%,对近地表风沙流控制效果最为明显。综合对比分析,纱网沙障最优设置模式为:沙柳防护带迎风侧3倍障高处,与地面夹角45°。

Road surface and highway pavement would be easily damaged by wind erosion and sand burial during stumping convalescence of Salix psammophila protective belt on the desert crossing highway.Therefore,the gauze sand barrier was set up for protection of road surface,and its mode of arrangement high limit sand resistance and sediment transport were explored.On the windward side of S.psammophila protective belt,the gauze sand barrier was set at different angles and at different distances of S.psammophila protective belt s windward side.The wind speed and sediment transport rate were observed,and the roughness was analyzed in different modes.As the distance from gauze sand barrier to S.psammophila protection belt varied,the results showed that the distribution of wind speed flow isoline was different.The isoline was the densest when the distance was 3 times greater than the barrier height.In addition,the corresponding position with the maximum attenuation of wind speed was within the scope of the S.psammophila protective belt.And the maximum rate of the wind speed reduction and recovery were compared with the other two distance arrangements.The surface roughness within S.psammophila protective belt was markedly increased and greater than the open field(more than 7.33 times),and the best setting angle was 45°.The reduction of the sediment transport rate decreased with the increase of the setting angle of the gauze sand barrier,and all of them were greater than 88.08%.The effect of control to wind sand flow on surface was the most obvious when the gauze sand barrier was 3 times greater than barrier height from S.psammophila protective belt,and the average of transport rate was 89.14%.Above all,the optimum mode of arrangement gauze sand barrier should be set 3 times greater than the barrier height and had an angle of 45°.