A study on the mesoscopic damage of asphalt mixture under freeze-thaw cycles based on discrete element theory

In order to study the damage and failure of asphalt mixture under uniaxial loading under freeze-thaw cycle, a damage constitutive model is constructed based on the Particle Flow Code (PFC2D). Through four sets of uniaxial compression laboratory tests with different freeze-thaw cycles, numerical simulation with the help of PFC2D, analysis of macroscopic failure of asphalt mixture and evolution law of internal microcracks from mesoscopic perspective, the equation of the relationship between the damage variable and the strain is established. The results of the study showed that: (1) The numerical simulations are in good agreement with the experimental results. (2) The increase of freeze-thaw cycles will increase the freeze-thaw damage variable and peak strain of asphalt mixture and reduce the compressive strength of asphalt mixture. (3) The established piecewise function expression can fit the relationship between the damage variable and the strain well. This study provides a convenient method for the mesoscopic study of asphalt mixture loading test under freeze-thaw cycle.