泡沫塑料滤层的雨洪入渗物理淤堵模拟试验研究

泡沫塑料是一种新型滤层材料,在海绵城市入渗系统中具有较好的应用前景,迄今仍存在不同雨洪悬浮物特征下滤层规格的选取以及淤堵之后如何维护等疑难问题。针对雨洪悬浮物淤堵问题,通过在典型场地取样调查分析,得出研究区域雨洪悬浮物粒径级配及浓度范围,采用室内试验来模拟泡沫塑料滤层的物理淤堵过程。将雨洪颗粒划分为5个粒组,分别制备悬浮物溶液,系统开展了滤层入渗模拟试验,建议了滤层选型原则。即对于粒径[0.1,0.25) mm以及<0.1 mm的细颗粒,与其相对应的具有最佳截留效果的滤层规格分别为80 ppi和100 ppi。采用组合级配悬浮物颗粒制备不同浓度的悬浮物溶液,针对两种规格的滤层,开展了入渗模拟试验,获得了泡沫塑料滤层渗透系数下降速度随悬浮液浓度的变化规律。即相同滤层孔径下,雨洪悬浮物浓度越高,滤层淤堵速度越快;相同悬浮物浓度下,滤层孔径越小,淤堵速率越快。滤出液浊度的分析结果也证明了渗透系数的变化规律。

Simulation Test on Physical Clogging of Foam Plastic Filter Infiltrated with Storm-water

As a novel filter layer material, foam plastic has good application prospects in the sponge city infiltration system. Yet, the selection of filter layer specifications in the presence of different storm-water suspended solid characteristics and the maintenance of filter layer after clogging are still problems to be solved. In view of this, we acquired the particle size gradations and concentration ranges of storm-water suspended solids in the study area through sampling and analysis at a typical site, and then simulated the physical clogging process of foam plastic filter layer via indoor tests. We divided the storm-water particles into five groups according to their gradations and prepared suspension solutions respectively for the filter layer infiltration simulation test. We suggest that for fine particles of [0.1,0.25) mm and <0.1 mm, the pore size of the corresponding filter layer with the best retention effect is 80 ppi and 100 ppi, respectively. Moreover, we prepared solutions of various concentration with suspended solid particles of combined gradations to carry out infiltration simulation experiments for two types of filter layers, and obtained the change rules of the dropping rate of foam plastic filter layer's permeability coefficient with the suspension concentration as follows: in the presence of the same filter pore size, greater concentration of rainwater suspended solid led to larger clogging rate; at the same suspension concentration, smaller pore size of filter gave rise to faster clogging. The changes in permeability coefficient were also proven by turbidity analysis results of the filtrate.