| The drainage pavement plays an important role in the sponge design of the city.Although relevant research and engineering applications have been carried out,they are still in their infancy.The problem of coordination between the requirements of sponge city and the performance requirements of pavement is urgent to be solved.Therefore,the optimal design of pavement structure and material for drainage pavement is studied in this paper.First,a field survey of the service status of the drainage walkway was conducted and the attenuation law of permeable brick and concrete in the actual environment is obtained.Based on the indoor and outdoor test results,construction technology,pedestrian traffic volume and other factors,the causes of typical diseases were analyzed.After six months of operation,the attenuation rate of permeable brick pavement was very low.The width of brick joint has great influence on its permeability.The pavement flatness of permeable brick pavement is poor and the anti-skid property is good.The attenuation rate of pervious performance of pervious concrete pavement after 13 month of operation is very low.The pavement flatness of permeable concrete pavement is poor,the anti-skid performance is insufficient,and the strength destruction is rare.The permeable pavement of polyurethane gravel mixture has excellent permeable performance.The road surface is smooth,but the anti-skid performance is seriously insufficient.In view of the shortcomings of the existing indoor and outdoor permeable test methods,a permeable test method based on raindrop drop kinetic energy was proposed.In China,12 mm head height can be used for indoor and outdoor permeability test.In this paper,a constant head permeameter in overflow chamber is developed and the outdoor double-ring seepage meter was improved based on Fluent software In order to evaluate the permeability of permeable pavement under real rainfall conditions.Secondly,the standard value of crowd load is modified according to the characteristics of pedestrian load.The finite element software ABAQUS was used to verify the carrying capacity of conventional drainage walkways.From the perspective of pervious function,the pavement structure is optimized by using the improved pervious layer thickness checking model.The addition of low permeability baffle on the outside of the permeable base improves the water storage function of the drainage pavement and significantly reduces the pressure of the drainage system.Based on the orthogonal experiment,the influence law of the rainfall parameters in the recurrence period and the pavement design parameters such as the thickness of permeable layer on the seepage performance of the drainage pavement was studied.Finally,the pervious capacity of pervious concrete pavement was designed with the goal that the pervious performance of pavement could still meet the design requirements when the void was blocked and stabilized,and the pervious concrete pavement’s pervious capacity was designed with comprehensive consideration of the factors such as construction technology and design rainfall intensity.From the Angle of walking safety and permeable,the design standard of crack type pavement brick is put forward,and the maximum width of crack should not exceed8 mm.The circular short pipe model with butterfly valve at the outlet is used to calculate the permeability of the gap drainage pavement without filler.These measures provide reference for the reasonable selection of pervious materials.Combined with an example,this paper recommends the pavement structure of crevasse drainage pavement under different design rainfall conditions in nanjing,which provides reference for the construction of drainage pavement in this area. |
