预防性养护用薄层罩面疲劳破坏细观特性分析

为分析预养护后薄层罩面的疲劳破坏机理,文章通过室内试验与数值模拟相结合的方式,对含层间的沥青混合料试件进行三点弯曲破坏、三点弯曲疲劳试验。结果表明:宏、细观疲劳试验结果之间的差值在3%~5%,满足试验对误差的要求;薄层罩面的弯曲疲劳寿命与加载频率呈正相关,与荷载应力呈负相关;疲劳过程中裂缝分为萌芽、发展、扩展3个阶段,0.2 $ N_{f} $~ $ 0.8N_{f} $为裂缝发展阶段,这一阶段剪切型裂缝迅速发展;颗粒间的接触力链随着加载的进行逐渐断裂,且应力主要分布在裂缝顶端处;应力比越大、加载频率越低,加载初期因接触力链断裂而产生的滑移能增速越快。在薄层罩面的使用过程中,应注意避免前期性能损伤,以防止裂缝的快速扩展和耐久性的降低。

To analyze the fatigue failure mechanism of thin overlay after pre-curing, this paper combines indoor test and numerical simulation to carry out three-point bending failure and three-point bending fatigue tests on asphalt mixture specimens with interlayer. The results show that the difference between macro and micro fatigue test results is between 3% and 5%, which meets the requirements of the test for error. The bending fatigue life of the thin overlay is positively correlated with the loading frequency and negatively correlated with the load stress. The cracks in the fatigue process are divided into three stages: germination, development and expansion. The interval from $ 0.2N_{f} $ to $ 0.8N_{f} $ is identified as the stage of crack development, and the shear cracks develop rapidly in this stage. The contact force chain between the particles gradually breaks with the loading, and the stress is mainly distributed at the top of the crack. The larger the stress ratio and the lower the loading frequency, the faster the growth rate of slip energy caused by the fracture of the contact force chain at the initial stage of loading. Therefore, in the process of using the thin overlay, attention should be paid to avoid the early performance damage, so as to prevent the rapid expansion of cracks and the decrease of durability.