沥青路面多尺度结构的荷载响应分析

Numerical Analysis on Multi scale Structure of Asphalt Concrete Pavement

关键词:  道路工程  沥青混凝土  多尺度  离散元方法  细观结构

Key words:  road engineering  asphalt concrete  multi scale  discrete element method  mesostructure

摘要:

为了从材料细观结构角度研究沥青路面结构的荷载响应，采用离散元方法，建立了柔性基层沥青路面典型结构模型，并进行了竖向荷载作用下沥青混凝土层应力和应变的计算，通过与经典路面响应程序计算结果的比较，验证了路面结构离散元模型和离散元计算方法的正确性.以验证过的路面结构模型为基础，采用较小的细观尺度描述了沥青混凝土结构层底部位置处粗集料、沥青砂浆和空隙的分布和体积大小，从而建立了路面结构的多尺度模型，并计算了荷载作用下多尺度模型的响应.结果表明，荷载引起的路面结构应力和应变在沥青混凝土内呈现显著的不均匀分布特征；粗集料与砂浆接触处的应力明显高于沥青砂浆内部的应力，两者的比值随着沥青砂浆模量的降低而增大；考虑材料细观结构后，粗集料与砂浆接触处的荷载响应明显高于宏观路面结构响应，而沥青砂浆内部的荷载应力小于不考虑细观结构时的宏观路面结构应力.

Abstract:

In order to explore the stress and strain relation in the pavement layers under traffic load from a meso structural perspective, the single scale discrete element model of asphalt pavement structure was built using discrete element method(DEM). The stress and strain at the bottom of the asphalt concrete layer under vertical load were calculated. The validation of discrete element model of asphalt pavement structure was conducted by the comparison of discrete element prediction with the results from the classical program. The distribution and volumetric fraction of coarse aggregate, asphalt mastic and air voids were taken into consideration at the bottom of the asphalt layer in the validated discrete element model to build the multi scale structure of asphalt concrete pavement. The tensile stress and strain in asphalt mastics and interface between aggregate and mastic were obtained and compared with the results from the single scale model. Results show that the stress and strain in multi scale structure is heterogeneous distribution. The tensile stress at the interface between aggregate and mastic is much higher than that in mastic. The ratio of stress at interfaces to the stress in mastics increases as the mastic stiffness decreases. The pavement design based on single scale model may underestimate the tensile stress at interface between aggregate and mastic and overestimate the tensile stress in mastic.