Study On Influence Of Homogeneity On Mechanical Properties Of Asphalt Mixtures Based On Discrete Element Method

Asphalt mixture is a kind of complex strong bonding particle system, which has the obvious characteristics of nonlinear mechanics. Compared with the continuum mechanics method, the discrete element method considering the particle system and the nonlinear characteristics of asphalt mixture, at the same time, the internal stress of the asphalt mixture can be quantified in the loading process, so it is more suitable to simulate the mechanical behavior of asphalt mixture.Most of the current problems already can be solved by the two-dimensional discrete element model, but the two-dimensional discrete element can not simulate the complex internal structure of asphalt mixture, and also can not truly reflect the viscoelastic properties. In this paper, based on the CT technology and digital image processing method, numerical simulations are conducted to study the high and low temperature performance of asphalt mixture and shear performance using PFC3D, which is a kind of software of the three-dimensional discrete element. At the same time, combined with the overall index of homogeneity of asphalt mixture, we explore the Influence mechanism of fine microstructure on the mechanical properties of asphalt mixture.Based on the CT technology and the digital image processing method, we introduce and implement a3D discrete element reconstruction of asphalt mixture and the process of numerical simulation. Aggregate uses actual boundary, and given the contact bond model and Burgers viscoelastic model, we simulate the splitting test at low temperature, uniaxial compression test, shear test and uniaxial static creep test of asphalt mixture at high temperature, at the same time, combined with the overall index of homogeneity of asphalt mixture, analyzing the relationship between micro structure and macro mechanical properties of asphalt mixture, and it is verified by laboratory test. Then, based on the indoor test, we compared and analyzed the difference of3D discrete element method and2D discrete element method, and analyzed their characteristics respectively. Finally, we analyzed the effects of geometric model, the model parameters and the load boundary condition on the numerical simulation of three dimensional discrete element.The results of the study show that the internal structure of asphalt mixture can be easily obtained based on CT technology and digital image processing techniques. Three dimensional discrete element method can be used to simulate the mechanical characteristics of asphalt mixture, combined with the overall homogeneity of asphalt mixture, it can also be used to establish the connection between fine microstructure and the variation of mechanical properties asphalt mixture. There is a good correlation between the overall homogeneity of asphalt mixture and variability of mechanical properties of asphalt mixture at high or low temperature. Compared to the two-dimensional discrete element method, the three-dimensional discrete element method is more suitable for the study on mechanical properties of asphalt mixture. In the three-dimensional discrete element modeling in the process, the geometric model, model parameters and loading conditions have impact on the simulation results in different degrees.