模拟降雨条件下重构阻水层对坡面风化煤矸石产流产沙的影响

[目的] 为缓解水分因子对高寒矿区扰动土体无法形成冻土带来的不利影响，研究提出扰动土体下方添加高阻水性材料亲水性聚氨酯(W-OH)重构底部阻水层(近似无缝隙的不透水层)的设计方案，分析重构阻水层后高寒矿区风化煤矸石坡面入渗、产流和产沙的变化特征，为高寒矿区扰动坡面冻土重现以及重构阻水层的坡面水土流失防治提供理论支撑。 [方法] 通过人工模拟降雨试验，研究在60和90 mm/h降雨雨强条件下，重构阻水层(添加W-OH浓度0%，1.5%，2.5%，3.5%，4.5%)后不同坡度条件的(3种坡度5°，15°，25°)的风化煤矸石坡面入渗特性和水土流失变化规律。 [结果] ①重构阻水层后的煤矸石坡面稳定入渗率较自然坡面明显降低，且与W-OH添加浓度呈负相关关系； ②煤矸石坡面产流率随时间变化呈现先快速上升后逐渐平稳的变化趋势，平均产流率与W-OH添加浓度呈现正相关关系，添加浓度为1.5%，2.5%，3.5%，4.5% W-OH的煤矸石坡面平均产流率较自然状态增加26.75%，38.02%，46.90%，63.23%； ③坡面平均流速与降雨雨强、W-OH添加浓度和坡度均呈正相关关系，影响程度表现为：降雨雨强＞坡度＞W-OH添加浓度。 ④坡面产沙率随时间变化曲线多为“单峰”曲线，呈现先迅速上升随后缓慢下降最终趋于稳定的变化趋势，添加浓度为1.5%，2.5%，3.5%，4.5% W-OH的煤矸石坡面平均产沙率较自然状态增加26.98%，49.48%，71.64%，94.01%。 [结论] 重构阻水层对坡面风化煤矸石渗透性能降低明显，能有效帮助高寒矿区扰动坡面的冻土恢复和形成，但入渗率的降低使坡面更容易产生径流，增加了地表的产流产沙，可配置一定的水土保持措施。

Effect of Reconstructed Water-blocking Layers on Sediment Production from Weathered Coal Gangue on Slopes Under Simulated Rainfall Conditions

[Objective] A design scheme was proposed involving the addition of hydrophilic polyurethane (W-OH, a highly water-resistant material) under disturbed soil conditions to reconstruct a bottom water-resistant layer (approximately seamless impervious layer) in order to alleviate the adverse effects of water factors on the failure of disturbed soil to form frozen soil in a high cold mining area. Changes in slope infiltration, flow production, and sediment production of weathered coal gangue after the reconstruction of a water-blocking layer in an alpine mining area were studied to provide theoretical support for the recurrence of frozen soil on a disturbed slope and the prevention and control of soil erosion on a slope after the reconstruction of a water-blocking layer. [Methods] Simulated artificial rainfall was applied at rates of 60 mm/h and 90 mm/h to reconstructed water-blocking layers having W-OH concentrations of 0%, 1.5%, 2.5%, 3.5%, and 4.5%. Infiltration characteristics and soil and water loss changes of the weathered coal gangue slope under three different slope conditions (5°, 15°, 25°) were obtained. [Results] ① The stable infiltration rate of the coal gangue slope after application of a reconstructed water-blocking layer was significantly lower than that of natural slope, and was negatively correlated with W-OH concentration. ② The flow yield of the coal gangue slope showed a trend of rapid increase at first and then gradually becoming stable over time, and the average flow yield showed a positive correlation with the W-OH addition concentration. The average runoff yield of coal gangue slopes with 1.5%, 2.5%, 3.5%, and 4.5% W-OH increased by 26.75%, 38.02%, 46.90%, and 63.23%, respectively, compared with the natural state. ③ The average slope velocity was positively correlated with rainfall intensity, W-OH addition concentration, and slope, and the influence degree followed the order of rainfall intensity＞slope addition concentration＞W-OH addition concentration. ④ The variation curve of slope sediment yield over time was mostly a “unimodal” curve, which showed a rapid rise at first, then a slow decline and finally tends to be stable. The average sediment yield of coal gangue slopes with 1.5%, 2.5%, 3.5%, and 4.5% W-OH increased by 26.98%, 49.48%, 71.64%, and 94.01% compared with the natural state. [Conclusion] The reconstructed water-blocking layer significantly reduced the permeability of weathered coal gangue on the slope, thereby effectively helping the recovery and formation of frozen soil on disturbed slopes in high, cold, mining areas. However, the decrease in infiltration rate could make the slope more prone to runoff and increases sediment production on the surface, and therefore, certain soil and water conservation measures should be applied.