Abstract: In order to study the plastic deformation accumulation of asphalt mixture, Burgers model was used to fit the creep process of gussasphalt at 60 ℃. However, the plastic viscous deformation rate calculated by the inversion parameters was always greater than the measured total deformation rate, and the calculated residual strain was far less than the measured value. Although the defect of residual strain was overcome by using the improved model with instantaneous plastic strain, the deformation rate still had a large deviation, which made the subsequent loading and unloading process incalculable. In view of the above problems, a new Burgers model with elastic limit σe was constructed. The new model and Burgers model were identical equation. But the instantaneous deformation was separated into elastic terms and plastic terms through σe, and viscoelastic deformation in Burgers model was separated into viscoelastic terms and viscoplastic terms. The proportion of the two separations was the same, and the stress-strain relationship in plastic and elastic stages was the same. The physical mechanism of the viscoplastic term added in the new model was the plastic dislocation and rotation of meso-components. In the subsequent loading, due to the material hardening, the load was equal to σe. The Burgers model with σe as the load was obtained by the term elimination of the new model. The fitting results show that the new model not only solves the deformation rate problem of the improved model with instantaneous plastic strain, but also can accurately calculate the subsequent loading and unloading process, which provides a tool for the calculation of plastic cumulative deformation of asphalt mixture.

Key words: highway engineering; constitutive relation; repeated creep; deformation accumulation; asphalt mixture

摘要： 为研究沥青混合料塑性变形积累，用Burgers模型拟合了浇注式沥青混合料60 ℃蠕变过程，但由反演参数计算的塑性黏滞变形速率却始终大于实测的总变形速率，且计算的残余应变也远小于实测值。采用含瞬时塑性应变的改进模型后，虽然克服了残余应变的缺陷，但变形速率仍存在很大偏差，更不能计算后续加卸载过程。针对上述问题，构建了含弹性极限σe的Burgers新模型，新模型与Burgers模型为恒等式，但通过σe将瞬时变形分离为弹性与塑性2项，将Burgers模型中的黏弹性变形分离为黏弹与黏塑2项，2种变形分离的比例相同且塑性和弹性阶段的应力应变关系相同；新模型增加的黏塑性项物理机制为细观成分的塑性错动与旋转。后续加载中，因材料硬化，荷载等于σe，新模型消项得到以σe为荷载的Burgers模型。拟合结果证明：新模型不仅解决了含瞬时塑性应变改进模型的变形速率问题，也能准确计算后续加卸载过程，为沥青混合料塑性积累变形计算提供了工具。

关键词: 道路工程; 本构关系; 重复蠕变; 变形积累; 沥青混合料