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动态回弹模量的滞回曲线是动态加载作用下混合料的荷载和变形曲线,可反映沥青混合料内部应力应变状态随荷载和温度等的演变规律。基于黏弹理论可确定滞回曲线的3种形态参数:长轴斜率k、椭圆离心率e、滞回曲线面积S,分别表征沥青混合料的动态回弹模量、黏滞性及耗散能。并由此进行不同温度、荷载的动态回弹模量试验,结果发现:随温度升高SBS与70#沥青混合料形态参数存在较大差异,且其变化曲线均在15~20℃出现明显拐点;随荷载级位变大k,S呈一定的变化规律但e值基本不变。表明:(1)相对级配而言,沥青品质对混合料性能影响更大,而黏滞性与荷载大小无关;(2)在15~20℃间沥青混合料的力学性能差异较大,对温度的敏感性较高;(3)不同的滞回曲线形态参数取值体现了沥青混合料间的性能差异,可以采用3种形态参数对沥青混合料的黏滞性、耐疲劳性等基本力学性能进行评价。最后,基于试验曲线的变化规律,建立了回弹模量的应力依赖性模型,可反映不同应力水平条件下沥青混合料的响应行为,且预测结果较接近真实状态;基于Miner线性损伤准则,推导了变荷载累积耗散能预估方程,并建立了基于能量耗散理论的疲劳方程,可以通过动态模量试验得到的形态参数S对混合料疲劳性能进行预测。
The hysteresis curve of dynamic resilience modulus is the load and deformation curve of the mixture under dynamic loading, which can reflect the evolution law of the internal stress and strain of asphalt mixture with load and temperature. Based on the theory of viscoelasticity, three kinds of morphological parameters of hysteretic curve can be determined: long axis slope k, elliptic eccentricity e and hysteresis curve area S, which respectively characterize the dynamic resilience modulus, viscosity and dissipation energy of asphalt mixture . The results show that the morphological parameters of SBS and 70 # asphalt mixture vary greatly with increasing temperature, and the curves of them all show obvious inflection points at 15 ~ 20 ℃ ; With the load level becomes larger k, S showed a certain variation but the value of e was basically unchanged. The results show that: (1) Asphalt has a greater influence on the properties of the mixture than the grading, while the viscosity has no relation with the size of the load; (2) The mechanical properties of the asphalt mixture vary greatly between 15 and 20 ℃, (3) Different hysteresis curve parameters reflect the performance difference between asphalt mixtures, and the three mechanics parameters such as viscosity, fatigue resistance and other basic mechanics of asphalt mixture can be adopted. Performance evaluation. Finally, based on the variation of the test curve, a stress-dependent model of resilience modulus is established, which can reflect the response behavior of asphalt mixture under different stress levels and the prediction results are closer to the real state. Based on the Miner linear damage criterion Based on the energy dissipation theory, a fatigue equation can be established, and the fatigue behavior of the mixture can be predicted by the morphological parameter S obtained from the dynamic modulus test.