Research On High-temperature Deformation Behavior Of Asphalt Mixture Using Discrete Element Method

Various kinds of damage appeared during service period of asphalt pavements,and rutting has been one of the major damage of asphalt pavements,and it severely affects traffic safety.Currently,the rutting research of asphalt pavement is mostly focused on experimental methods based on experimental phenomena.However,this method is time-consuming and costly.It is necessary to establish a means of numerical methods to analyze the high temperature deformation behavior of asphalt mixture.In this paper,the 3D virtual rutting test model base on PFC were developed to analyze the high temperature deformation behavior of asphalt mixture from micro-scale perspective.The major works of the paper are listed as follows:Firstly,the algorithm of generating 3D digital specimen of asphalt mixture was developed.For simulation of aggregates with irregular shapes,Polyhedron with selected size and irregular shapes was generated and imported into PFC.for random packing of aggregates in the specimen,two certain algorithms were listed for choosing based on specimen size and ratio of aggregates by volume.For simulation of asphalt mastics and air voids,the algorithm to distinguish asphalt mastics and aggregates after replacement with regularly arranged balls was developed,based on aggregates models.Air voids were generated by deleting some mastic balls.2D digital specimen was generated by installing section balls to record aggregates position of on 3D specimen section.Secondly,on the basis of analyzing the characteristics of all kinds of PFC contact models and micro-scale contact behavior of asphalt mixture during high temperature deformation,the contact model of mastics and aggregates in asphalt mixtures were choosing.The relationship between PFC model parameters and laboratory parameters was built.On the reference of existed documents or by experience,the model parameters was decided for virtual rutting test.Thirdly,on the basis of rutting test 3D specimen of asphalt mixture,the virtual rutting test was carried on in PFC3D.The distribution of contact force and displacement,the movement and rotation information of aggregates of rutting test specimen were recorded and analyzed,which practically reveals the mechanism of rutting in asphalt mixture.Finally,the influence of coarse aggregate content,flaky aggregate content,aggregate surface texture,air void fraction,load level and boundary assumption on virtual rutting test was evaluated.And the reasonable suggestions to improve the high-temperature stability of asphalt mixture were proposed.