储水式复杂型生物滞留设施的渗透系数试验研究

Permeability Coefficient Test of Complex Bioretention System with Internal Water Storage

采用常水头和降水头渗透试验测定储水式复杂型生物滞留设施的种植介质层、碎石排水层(含过渡层和穿孔管)和中试装置(未种植植物)的渗透系数。结果表明,釆用常水头渗透试验测得种植介质的渗透系数为197mm/h、孔隙比为0.68,中试装置中种植介质的孔隙比为0.76、渗透系数预测值为406mm/h;采用降水头渗透试验测得中试装置的等效渗透系数为650mm/h,碎石排水层的渗透系数为19129mm/h。储水式复杂型生物滞留设施的等效渗透系数由种植介质的渗透系数主导控制,受碎石排水层的渗透系数影响甚小,但受碎石排水层的厚度影响较大。

The permeability coefficients of the planting media layer, the gravel drainage layer (including transition layer and perforated pipe) and the pilot bioretention system ( no plant) with internal water storage were determined by the constant-head test and falling-head test. The results showed that the permeability coefficient of the planting media and the void ratio were 197 mm/h and 0. 68 by the constant-head permeability test, and the void ratio and predicted permeability coefficient of the planting media in the pilot bioretention system were 0. 76 and 406 mm/h. The measured equivalent permeability coefficient of the pilot bioretention system was 650 mm/h by the falling-head test, and the permeability coefficient of gravel drainage layer was 19 129 mm/h. The equivalent permeability coefficient of the complex bioretention system with intenial water storage was dominated by the permeability coefficient of the planting media. It was rarely affected by the permeability coefficient of the gravel drainage layer, however, it was greatly affected by the thickness.