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通过自制试验装置研究了强降雨条件下含非饱和导排层的毛细阻滞型覆盖层性能,试验装置包括2 m×1 m×1.2 m的模型槽、降雨模拟器与测量系统等。毛细阻滞型覆盖层模型中细粒土、非饱和导排层和粗粒土分别采用粉土、砂和碎石,模型坡度为1V∶3H,共进行3组试验。所模拟的强降雨强度为65～76 mm/h,利用摄像和张力计监测了降雨入渗及侧向导排过程,并分别监测了坡面径流量、各土层的侧向导排量及底部渗漏量随时间变化。在强降雨条件下,试验Ⅰ中坡面径流量占降雨量的69.4%,入渗的水量中大部分存储在上层粉土中,砂层的侧向导排量为降雨量的3.5%,碎石层底部的渗漏量只有降雨量的2.9%。试验Ⅱ和试验Ⅲ中通过添加膨润土降低粉土层渗透性有效减少了降雨入渗量,与试验Ⅰ相比,试验Ⅱ和试验Ⅲ中非饱和砂层侧向排水出现时间延后,试验Ⅱ中通过下卧碎石层渗漏量进一步减少至0.8%,试验Ⅲ中无渗漏。试验结果表明:通过控制上层土降雨入渗量及发挥毛细阻滞及侧向导排综合作用,可有效控制该覆盖层在强降雨条件下渗漏量,使毛细阻滞型覆盖层在湿润气候区应用成为可能。
The performance of the capillary retarded coating with unsaturated guide layer under heavy rainfall conditions was studied by a self-made test device. The test device includes a 2 m × 1 m × 1.2 m model tank, a rainfall simulator and a measuring system. Fine grained soil, unsaturated graded layer and coarse grained soil were used in the model of capillary retardation cover. Silt, sand and gravel were used respectively. The slope of the model was 1V: 3H. A total of three experiments were carried out. The simulated rainfall intensity was 65-76 mm / h. Rainfall infiltration and lateral drainage were monitored by using camera and tension meter. Slope runoff, lateral drainage and bottom seepage The amount of leakage varies with time. Under heavy rainfall condition, the runoff of slope in experiment Ⅰ accounted for 69.4% of the rainfall, most of the infiltration water was stored in the upper silt, lateral discharge of sand was 3.5% of the rainfall, gravel The amount of leakage at the bottom of the layer is only 2.9% of the rainfall. In experiment Ⅱ and experiment Ⅲ, the permeability of silt layer was reduced by adding bentonite, which effectively reduced the rainfall infiltration. Compared with experiment Ⅰ, the lateral drainage time of unsaturated sand layer in tests Ⅱ and Ⅲ was delayed. In experiment Ⅱ Leakage through the gravel layer further reduced to 0.8%, no leakage in test Ⅲ. The experimental results show that the amount of seepage under the heavy rain can be effectively controlled by controlling the rainfall infiltration of the upper soil layer and exerting the capillary blockage and the combined effect of lateral drainage and drainage so that the capillary- Application becomes possible.