| With the process of rapid urbanization,a large number of natural surfaces are replaced by impermeable pavements.The pa-vement runoff pollution has become one of the main sources of surface pollution due to the influence of atmospheric settlement,waste accumulation,exhaust emission and oil leakage.Most of the pollutants in the pavement runoff are carried into surrounding water or soil,which seriously affects the ecological balance of the city.Therefore,effective control of pavement runoff pollution has become an urgent problem to be solved in urban ecological construction.On the basis of a comprehensive comparison of various measures for the treatment of runoff pollution,the treatment technology of runoff pollution in the source position,such as permeable pavement and ecological drainage are considered as effective measure for the control of pavement runoff pollution.Therefore,the road surface and the edge ditch were taken as the structure modules in this paper,and the loose granular purification layer and pervious concrete were selected as the research objects because of the wide application range,flexible use and good purification effect.(In this paper,this two were combined as "infiltration structure").On the basis of the survey of road runoff water quality,the effects of material,structure and hydraulic parameters of filtration structure on the pollution of road surface runoff were studied.Through a variety of test methods,the purification mechanism of the infiltration structure was deeply analyzed,and the long-term effect mechanism of blocking the pavement runoff pollution was explored.The investigation and analysis of the typical road runoff in Yangzhou showed that the pollution of pavement runoff was serious and the first flush effect was obvious.The phenomenon of pollution enrichment was shown in the vicinity of the intersection and a large number of pedestrians.It showed that the removal of suspended particles was an effective way to control pavement runoff pollution,and the main particle size range of suspended particles was determined.The filtration of suspended particles in this particle size made the purification of pavement runoff pollution more effective.Through the filtration test of 5 kinds of materials,3 kinds of pavement thickness(10cm,20cm,30cm)and 3 kinds of material granular size(1～3mm,3～6mm,6～8mm),it was found that the purification effects of different loose granular purification layers on runoff pollutants were different,and the comprehensive purification ability of 5 kinds of loose granular purification layer was the zeolite>slag>volcanic>ceramsite>diatomite;the thickness of loose granular purification layer and material granular size were recommended for different runoff pollutants,and the composite form of material suitable for different road runoff pollution types was also recommended by fuzzy comprehensive evaluation method.Through the study of the basic performance test and filtration test of pervious concrete,the relationship model of the porosity of pervious concrete with the compressive strength,the permeability coefficient and the purification rate of the pollutants was established,and a calculation method for the void ratio of the pervious concrete based on reducing the runoff was proposed,and the compression strength,water permeability and purification effect were taken into account.The void ratio of pervious concrete was about 20%.It was found that the particle size distribution changed in three points,(1)the change of the particle size range,(2)the change of the peak shape characteristics,(3)the decrease of the maximum particle size,and the particle size range of 161～800μm and 417～800μm,respectively,in the loose particle purification layer and the pervious concrete.The retention of suspended particles was the best.The microscopic image observation and elemental analysis of loose granular materials showed that the removal of suspended particles by zeolite and diatomite was dominated by structural space intercepting,and volcanic,ceramsite and slag were completed by the interaction of pore adsorption and structural gap interception;the adsorption of 5 loose granular materials on TN,TP,Zn and Pb The results were in agreement with the results of the percolation test.The results of the long simulated periodic percolation test of the infiltration structure showed that the permeability coefficient of the infiltration structure had a negative correlation with the purification rate of the pollutants,and the clogging process of the filtration structure was divided into three stages:"fast blocking","blocking partial recovery" and "progressive obstruction".The purification process was divided into three stages:"rapid upgrading of purification capacity","slow upgrading of purification capacity" and "slow reduction of purification capacity".The method of determining the best cleaning time of the infiltration structure was put forward,and the space blockage of loose granular purification layer and pervious concrete was the most serious in the gap between 30～70mm and 0～30mm below the surface.respectively.This study aims to promote the application of source control technology in pavement runoff pollution treatment and play a role in evaluating the pollution status of road environment before and after the implementation of source control measures. |
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