沥青混合料拉压疲劳损伤试验

为研究沥青路面结构实际处于拉压应力作用下的疲劳损伤特性,针对沥青混合料AC-13开展了连续式交变正弦波形加载的小梁拉压疲劳试验。依据损伤力学基本理论,采用唯象学方法分析了沥青混合料的拉压疲劳损伤特性。介绍了拉压疲劳试验方法及影响因素,根据疲劳试验结果得到了拉压疲劳方程;基于弹性模量定义的损伤变量,建立了拉压疲劳损伤模型,拟合疲劳试验结果确定了损伤参数,获得了考虑应力水平的拉压疲劳损伤演化方程。研究结果表明:疲劳损伤参数α、β随应力水平增大而增大,且近似呈线性关系;拉压疲劳损伤演化大致呈3阶段变化规律,即损伤萌生、损伤稳定增长和损伤失稳破坏阶段;应力水平越大的损伤演化曲线越靠下,随寿命比变化疲劳损伤演化速度越缓和。

Experiment of Tension-compression Fatigue and Damage for Asphalt Mixture

In order to understand the fatigue damage characteristics of the actual structure of asphalt pavement under tension and compression stress,the tension-compression fatigue test of beam under continuous sine wave alternating loading for AC-13 was conducted.Based on the basic theory of damage mechanics,the tension-compression fatigue damage characteristics of asphalt mixtures were studied using phenomenology.The tension-compression fatigue test method and influencing factors were introduced,and the tension-compression fatigue equation was established by fatigue test results.Based on the damage variable defined by elastic modulus,the tension-compression fatigue damage model was established.The damage parameters were determined by fitting the fatigue test data,and the tension-compression fatigue damage evolution equation regarding to the stress level was built.The results show that(1) fatigue damage parameters α and β increased with stress level,and the relationship between the damage parameters and the stress level was linear;(2) tension-compression fatigue damage evolution was roughly three-stage variation,i.e.,damage initiation,damage stable growth and damage unstable failure;(3) the greater the nominal stress level,the lower the curve of damage evolution curve,and the more moderate the fatigue damage evolution speed varying with life radio.