关键词: 道路工程; 本构关系; 重复蠕变; 变形积累; 沥青混合料

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