Research On Water Infiltration And Storage Efficiency Of Full-Structure Permeable Asphalt Pavement

Over-hardening of urban ground makes the proportion of the urban permeable underlying surface become smaller,and the pressure of urban rainwater drainage systems continue to increase.The full-structure permeable asphalt pavement is a type of asphalt pavement structure that allows surface water to enter the surface layer,grassroots layer,and subgrade soil,which can reduce the urban surface runoff coefficient,the surface runoff rainwater pollutants and the road heat island effect,accordingly improve the usability of urban pavement.At present,the research of road engineering majors on permeable pavement mainly focuses on the performance of asphalt mixture,and the results of reducing surface runoff and alleviating urban drainage system load are insufficient.The permeation function of the full-structure permeable asphalt pavement includes penetration and water storage.Therefore,it is necessary to carry out research on the infiltration and storage efficiency,analyze the influence of various factors on the application effect of permeable asphalt pavement,and provide new ideas and methods for improving the design of permeation function.First,the permeation mechanism of full-structure permeable asphalt pavement was analyzed.On the basis of literature research,the process,characteristics and calculations of urban rainfall runoff-producing and flow concentration were analyzed.The calculation principle of urban stormwater runoff calculation model was analyzed.Based on the soil runoff mechanism,the runoff mechanism of the fully-structured permeable asphalt pavement was described by the "holding mechanism" and "interface flux mechanism",and the runoff mechanism of subgrade soil was analyzed.The infiltration and storage functions of the fully-structured permeable asphalt pavement were described.The rainfall parameters and permeability coefficients were analyzed.The rainfall intensity distributions of different rainfall return periods in Nanjing were obtained and the values of the permeability coefficients in the modeling process were given.Second,the permeability and water storage efficiency of the fully-structured permeable asphalt pavement were studied based on the SWMM model.The SWMM model’s low-impact development function and modeling data requirements were analyzed.SWMM modeling,parameter determination,and model parameter calibration for the study area were completed.The parameter setting and application effect evaluation method of permeable pavement LID facilities were studied.The rainfall data from different return periods in Nanjing was used to simulate the rainfall runoff,nodes,and pipe sections before and after the LID application in the study area,and study the effect of LID applications on permeable pavement on reducing surface runoff and alleviating drainage system load.Based on the simulation results of the SWMM model,the evaluation of the permeability and water storage efficiency of permeable asphalt pavement was completed.The permeable pavement in this paper can produce no road runoff in a torrential rain once in 50 years and can quickly drain the rainwater in the pavement structure.Finally,the factors that affect the permeability and water storage efficiency of the fully-structured permeable asphalt pavement were analyzed.Sufficient pavement structure thickness,voidage,and permeability coefficient of subgrade soil are important guarantees for the permeable pavement to have no “holding mechanism” runoff.The permeability coefficient of pavement structure determines whether the “interface flux mechanism” runoff will occur in the permeable pavement.Setting covered drain is an effective way to reduce the storage space required for pavement structure and reduce the thickness of the pavement structure.When there is no runoff in the area where permeable pavement is applied,the runoff reduction rate of permeable pavement under different rainfall return periods is almost the same,and there is a strong linear relationship.Based on the analysis results of the influencing factors,a full-structure permeable asphalt pavement application program was proposed in this paper.