基于应变控制的沥青混合料疲劳寿命预测

Prediction of Fatigue Life of Asphalt Mixture Based on Strain Control

在应变控制模式下对3种不同级配的沥青混合料进行了四点弯曲小梁疲劳试验,对采用耗散能相对变化率的突变点(判据1)和劲度模量下降至初始劲度模量的50%(判据2)两种失效判据得到的沥青混合料疲劳寿命进行了对比,并针对两种失效判据构建了疲劳寿命预测模型.结果表明:混合料的初始劲度模量随应变水平及公称最大粒径的增大而减小;以判据1为失效判据时,同一沥青混合料在不同应变水平下破坏时的劲度模量基本相同,不同沥青混合料破坏时的劲度模量随公称最大粒径的增大而减小,获得的疲劳寿命比以判据2为失效判据获得的疲劳寿命长;沥青混合料的疲劳寿命随应变水平及公称最大粒径的增大而大幅减小;判据1对应的疲劳寿命预测模型准确性更高.

Four-point bending beam fatigue tests of three kinds of graded asphalt mixtures were carried out in the strain control mode,and two criteria for fatigue life prediction,namely the catastrophe point of the relative change rate of dissipated energy （Criterion 1 ）and the stiffness modulus decreasing to 50%of the initial stiffness modulus （Criterion 2）,were compared.Then,two fatigue life prediction models respectively corresponding to the two crite-ria were constructed.The results show that （1 ）the initial stiffness modulus of the mixture decreases with the in-crease of strain level and nominal maximum particle size;（2）when Criterion 1 is used as the failure criterion,the same mixture mostly destroys with the same stiffness modulus at different strain levels,the destruction stiffness modulus of different mixtures decreases with increase of nominal maximum particle size,and the predicted fatigue life is longer than that predicted by Criterion 2;（3 ）the fatigue life of asphalt mixture significantly decreases with the increase of the strain level and the nominal maximum particle size;and （4 ）the fatigue life prediction model corresponding to Criterion 1 is of higher accuracy.