雨水花园过滤系统的渗透性能试验研究

Experimental study of permeability in rainwater garden filtration system

为了探讨雨水花园过滤系统内部渗滤过程、研究用于评价渗透过程的监测参数,采用脉冲示踪试验得到不同水力负荷条件下的水力停留时间分布密度曲线,根据表观水力停留时间和峰值水力停留时间之间的关系计算水力效率,并通过渗透特性试验得到水力负荷与渗透系数之间的关系.结果表明,雨水花园内存在非均匀性流场分布.当水力负荷为1.0 m3/(m2·d)时,雨水花园过滤系统中用于去除污染物的填料层有效体积比例最大,水力效率最高.淹没区下渗流态更接近推流流态.渗透系数与水力效率成反比例关系,与水力负荷成非线性关系.脉冲示踪试验结果和渗透特性试验结果共同验证了过滤系统渗流过程的四阶段假设.

To investigate the filtration process in the rainwater garden filtration system and study the monitoring parameters to evaluate the infiltration process, the hydraulic residence time distribution density curves under different hydraulic loads were obtained by using the pulse tracer tests. The hydraulic efficiency was calculated according to the relationship between the nominal hydraulic residence time and the peak hydraulic retention time. The relationship of the hydraulic load and the permeability coefficient was obtained by using the infiltration characteristic tests. The results show that there is the non-uniform flow field distribution in the rainwater garden. When the hydraulic load is 1.0 m^3/（m^2·d） , the effective volume proportion of the packing layer for removing pollutants is the largest and the hydraulic efficiency is the highest. The seepage flow in the submerged area is closer to the push flow. The permeability coefficient has the inverse relationship with the hydraulic efficiency, and the nonlinear relationship with hydraulic load. The 4-phase assumption of the filtration process is verified by the experimental results of the pulse tracer tests and the infiltration characteristic tests.