Drainage Pavement Design Based On Strength Characteristics Of Porous Asphalt Mixture

The drainage asphalt pavement can quickly remove the road surface water,reduce the drift,water mist,and improve traffic safety.In recent years,the concept of "Sponge city" has become more and more popular,while the research of drainage pavement structure and evaluation methods are less.The strength of porous asphalt mixture is lower than traditional graded asphalt mixture,which affects the bearing capacity and service life of the pavement structure.Therefore,based on the strength characteristics of porous asphalt mixture,this paper studies the capacity of permeable asphalt pavement structure,evaluates the applicability of permeable asphalt pavement structure under different traffic loads,and puts forward the design method of permeable asphalt pavement structure.Firstly,the compaction characteristics of porous asphalt mixture affect its strength and function characteristics.By analyzing the change of porosity,skeleton contact state and cantabro loss with the number of compaction times,to obtained the reasonable compaction times of porous asphalt mixture.The results show that the reasonable compaction times of the porous asphalt mixture should be between 45-77 times.Secondly,the skeleton penetration test is proposed to evaluate the skeleton strength of the mixture.the triaxial compression test is to evalutate the shear strength,and the two-dimensional image processing is to evalutate the aggregate contact property.The AC-13 mixture is used as the comparative test.The results show that the shear strength index c and(p of the porous asphalt mixture are less than AC-13,and the aggregate contact points is less than AC-13.Asphalt mortar and aggregate contact points are the key factors that affect the strength of porous asphalt mixture.Then,three typical drainage pavement structures were designed,which were single-layer drainage asphalt pavement structure,double-layer drainage asphalt pavement structure,three-layer drainage asphalt pavement structure,and analyze the stress characteristics of the pavement structure.The results show that the pavement structures designed in this paper can meet the design requirements under heavy traffic.Finally,a full-thickness triaxial multi-stage loading test based on the axle load spectrum data of the expressway is designed.The test method is used to analyze the strength of the permeable pavement structure.The results show that the carrying capacity of the single-layer drainage pavement structure is the strongest,and the fiber can greatly enhance the pavement service life.Compared with the single-layer drainage pavement structure,the carrying capacity of double-layer and three-layer drainage pavement structure is greatly reduced.Based on the MFN,the traffic level of different drainage pavement structure is evaluated.The single-layer drainage structure is suitable for heavy traffic grade,double-layer and three-layer drainage pavement structure is suitable for medium traffic grade.