基于黏弹特性的沥青疲劳损伤演化规律分析

The fatigue mechanism of asphalt by the change of the parameters of the asphalt viscoelastic constitutive model during the fatigue process was analyzed. First, a cyclic frequency scanning-fatigue test was designed in combination with the conventional fatigue test and the frequency scanning test. Based on the tests, the fatigue evolution of two asphalt under strain control mode was analyzed. Then, the fatigue evolution of master curves in viscoelastic parameters during asphalt damage process was established. And the change rules of the characteristic parameters representing the state of asphalt structure were analyzed based on generalized Kelvin-Voigt model. Finally, based on sensitivity analysis, the fatigue damage variable of asphalt was put forward, and the fatigue evolution of asphalt fatigue was expounded. The results show that the asphalt master curves of viscoelastic parameters are all moving in negative direction at longitudinal axis in the process of asphalt fatigue with the mobile space changing. The phase angle versus frequency master curves gradually deviate from linear trend of the low frequency range in high frequency range. The length of the complex modulus versus phase angle master curves shows the trend of shortening first and then increasing. And the length of the loss modulus versus storage modulus master curves is shortened continuously. There are two obvious changes in the characteristic parameters of the generalized Kelvin-Voigt model with only E₂, E₃, E₄ and η₀. The parameter (E₂+E₃)/2 is chosen as the fatigue variable of asphalt. It is verified that the variation rule of fatigue variable is related to the mechanism of asphalt fatigue crack propagation.