沥青路面蠕变响应现场预估方法与试验

Field Prediction Method and Experiment on Creep Response of Asphalt Pavement

为了揭示在役沥青路面结构的黏弹特性,给基于黏弹性本构的沥青路面设计提供参考,针对现有沥青路面应变测试仍然基于弹性假设的现状,依据三维线黏弹本构理论,通过现场埋设应变和温度传感器,开展不同温度与轴载作用下的沥青路面静载蠕变试验。基于实测应变变化规律对现有表征沥青混合料黏弹性本构模型的适用性进行了判别,并分析温度、偏应力等外部影响因素对沥青层黏弹性参数的影响规律,由此建立沥青路面应变随外部因素变化的预估模型。结果表明:实测蠕变历时曲线呈现的黏弹特性很好地符合Burgers模型,拟合判定系数超过0.98;Burgers模型的4个参数(G_1,G_2,η_1及η_2)均随温度的提高而减小,随偏应力的增加而增大,与偏应力、温度分别呈良好的线性和指数函数关系,拟合相关系数均大于0.84,其中黏性参数η_1和η_2受温度和偏应力的影响显著;按应变预估模型计算得到的应变与同等工况下的实测应变历时曲线规律吻合,应变值的相对误差在10%以内,表明建立的基于三维黏弹本构关系的沥青面层应变预估方法合理、可行。

In order to reveal the viscoelastic characteristic of asphalt pavement structure in service and provide a reference for the asphalt pavement design based on the viscoelastic constitutive theory, static load creep tests on asphalt pavement were conducted under different temperatures and axle loads by means of temperature and strain sensors on the asphalt surface. The tests were designed by dint of the three-dimensional linear viscoelastic constitutive theory,in allusion to the situation that existing strain tests of asphalt pavement were on the basis of the elastic constitutive hypothesis. The applicability of existing constitutive models used to represent the viscoelasticity of asphalt layers were discriminated based on change laws of measured strain. The influence of external factors （including temperature, deviatoric stress, etc. ） on viscoelastic parameters of asphalt layers was analyzed. Hence, the prediction model on strain of asphalt layer changing with external factors was established. The results show that the viscoelastic properties presented by the measured creep duration curves are consistent with Burgers model. The determination coefficient is more than 0.98. Four parameters of Burgers model G1, G2, r/1 and r# decrease with the increasing temperature, and increase with the increase of deviatoric strain. The parameters have the good linear relationship with deviatoric strain and the exponential function relationship with temperature. Meanwhile, the correlation coefficients are more than 0. 84. Amongst the parameters, viscous parameters η1 and η2 were obviously affected by temperature and deviatoric strain. The strain calculated by dint of prediction model coincides with the measured strain in the same working condition. The relative error of their values is less than 10%, which shows that asphalt surface strain prediction method based on three-dimensional viscoelastic constitutive relationship is reasonable and feasible.