Study On Characteristics Of Runoff And Effluent Quality Of Permeable Brick Pavement System In Sponge City

In order to solve urban waterlogging and prevent groundwater resources from being polluted by surface runoff,the construction of"sponge city"has become a top priority in China.In this paper,Permeable Brick Pavement System（PBPS）,a sponge city engineering measure,is taken as the research object.Based on the Soil-Water Characteristic Curve（SWCC）of PBPS,the model of rainfall infiltration of PBPS and the model of heavy metal pollutants migration in runoff of PBPS is established respectively.Combined with the configuration parameters of part layers of PBPS and the external conditions,the influences of PBPS on the runoff generation and the effluent quality of the structural layer are analyzed,which provides suggestions on optimization for the PBPS engineering design and lays a theoretical foundation for the construction of sponge city.The results of the study are as follows:1)Taking comprehensive consideration of the ability of PBPS delay runoff generation time and the ability of PBPS remove heavy metal pollutants,medium sand is the best choice for leveling soil.2)According to the effluent quality of the structural layer,there is an optimum thickness ratio between the base layer and the cushion layer.When the rain intensity is4.45 cm·h^-1,rainfall duration is 6 hours and the ratio of base layer thickness to bedding layer thickness is 15:4,the desorption rate of each heavy metal pollutant in runoff by base layer reaches the lowest,and the average removal rate（（?）_w）of each heavy metal pollutant in structure layer effluent is at least 78.91%.3)PBPS runoff generation time is inversely proportional to rainfall intensity and soil initial moisture content respectively,while PBPS cumulative runoff is proportional to rainfall intensity and soil initial moisture content respectively.4)The concentrations of heavy metal pollutants in the effluent of PBPS structure layer(c_ew)are proportional to rainfall intensity and initial concentrations of heavy metal pollutants respectively,while removal rates of pollutants of the PBPS（R_w）,initial penetration time and total penetration time of base layer are inversely proportional to rainfall intensity and initial concentrations of heavy metal pollutants respectively.