降雨历时动态变化对临时苫盖措施坡面减流减沙效益的影响

工程堆积体具有独特的物质组成，其土壤抗侵蚀能力差，受暴雨冲刷极易导致水土流失，密目网苫盖作为一种重要的临时措施，定量揭示密目网苫盖的蓄水保土机理具有重要意义。为分析降雨历时动态变化对工程堆积体密目网苫盖减流减沙效益的影响，试验设计60,90,120 mm/h 3个降雨强度，对5°,15°,25°,35°共4个坡度的堆积体坡面在裸地和密目网苫盖处理下进行人工模拟降雨试验。结果表明：60 mm/h降雨强度时，密目网苫盖处理在15°～35°对坡面产流历时抑制作用显著(p<0.05),当大于60 mm/h时，在15°～25°可显著延长坡面产流历时(p<0.05);不同坡度下60 mm/h与90,120 mm/h降雨强度减沙效益差异显著(p<0.05),密目网苫盖处理减流减沙效益随降雨历时延长而减小，均在90 mm/h降雨强度达阈值；幂函数可很好地描述减流减沙效益随降雨历时的变化关系，效益衰减系数(b)随降雨强度增大陡增；密目网苫盖处理减流减沙效益随降雨历时变化可分为高效阶段、递减阶段和稳定阶段，最佳减流效益历时总体小于30 min,最佳减沙效益历时在20 min附近。综上所述...

Influence of Rainfall Duration Dynamic Changes on Flow Reduction and Sediment Reduction Benefits of Fine Mesh Net on Construction Spoil Deposits

The construction spoil deposits have a unique material composition, and its soil erosion resistance is poor, which is easy to cause water and soil loss owing to rainstorm. Hence, it is important to explore the mechanism of flow reduction and sediment reduction of fine mesh net. To analyze the influence of rainfall duration dynamic changes on flow reduction and sediment reduction benefits of fine mesh net on construction spoil deposits, three rainfall intensities (60~120 mm/h) and four slope gradients (5°~35°) were considered on fine mesh net role of reducing soil erosion on spoil deposits. The results showed that: Under a rainfall intensity of 60 mm/h, covering with the fine mesh net has a significant inhibitory effect on the initial runoff time at 15°~35° (p<0.05), while it can significantly prolong initial runoff time (15°~25°) when a rainfall intensity more than 60 mm/h (p<0.05). There was a significant difference in the sediment reduction benefits of 60 mm/h and 90 mm/h (120 mm/h) rainfall intensity under different slopes (p<0.05). The flow reduction and sediment reduction benefits of fine mesh net were decreased with the prolonging of rainfall duration, and reached the threshold at a rainfall intensity of 90 mm/h. The power function can describe the relationship between the benefits of flow and sediment reduction with the rainfall duration well, and the benefit attenuation coefficient(b) increased sharply with the increase of rainfall intensity. The flow reduction and sediment reduction benefits of fine mesh net cover can be divided into high-efficiency stage, decreasing stage and stable stage with the change of rainfall duration. In general, considering the development of soil and water conservation work in production and construction projects, it is recommended to use temporary cover when a short-duration (< 30 min) and heavy rainfall (< 90 mm/h) is the main rainfall in the construction area of production and construction projects, which can effectively reduce soil erosion. The research results can provide reference for the supervision of soil and water conservation of production and construction projects.