Meso-structural Character Analysis On The Rutting Of Asphalt Pavement Based On Discrete Element Simulation

Rutting is a common disease phenomenon of asphalt pavement.Traditional researches on rutting of asphalt pavement are mostly empirical methods based on macroscopic damage phenomena,which have disadvantages such as time-consuming,labor-consuming,poor stability and poor repeatability.In essence,asphalt mixture is an uneven,discontinuous and anisotropic material.However,in previous researches on asphalt pavement,it is assumed that the material of each layer of pavement is completely elastic and anisotropic,and the contact surface between layers is continuous,which is inconsistent with the reality of asphalt.The discrete element method(DEM)can effectively simulate the discrete characteristics of the asphalt mixture.Therefore,based on the theory of DEM,this paper analyzed the mechanical response of rutting failure in asphalt pavement from a mesoscopic perspective.Firstly,according to the specifications of asphalt pavement material selection for expressway,three asphalt mixtures are selected for a uniaxial compression test,and the stress-strain curves of three mixtures are obtained under 60?.Then the rutting test at 60? is completed according to standard test conditions to obtain the deformation amount of each specimen.There are two kinds of rutting thickness:50mm single-layer and 100 mm double-layer rutting specimen.Then,irregular coarse aggregates composed of spherical elements are formed in PFC3 D software,and a three-dimensional uniaxial compression model of asphalt mixture is established,which is composed of irregular coarse aggregate,asphalt mastic and void.Uniaxial compression numerical simulation is used to fit the stress-strain curve of the laboratory test results of each asphalt mixture specimen,and the mesoscopic parameters of each material at 60? are obtained.Then,the displacement of particles and the crack development in the model during the uniaxial compression simulation test are analyzed.Finally,the simulation of uniaxial compression of mesoscopic parameters are used in the single-layer and double-layer rutting specimen model.By coding theFISH language,wheel-road interaction is simulated in DEM rutting models for three single-layer and two combinations of double-layer rutting simulation.By comparing the simulation results with the laboratory rutting test results,the difference of rutting deformation of different mixtures is analyzed,and the displacement change,vertical shear stress distribution,vertical compressive stress distribution,and horizontal stress of particles in different rutting test models are analyzed from a mesoscopic perspective.The results show that the rutting deformation of the road surface mainly occurs in the middle of loading,and the internal stress of models with different materials varies greatly in the rutting deformation process.High-modulus asphalt mixture can effectively resist rutting deformation.