移动荷载作用下柔性路面多尺度结构的响应

为了研究移动荷载下路面结构内部细观结构的响应，采用离散元方法进行了多尺度路面结构移动荷载响应的分析．建立了柔性基层沥青路面典型结构的离散元模型，并计算了移动荷载作用下沥青层底的应力和应变，通过与已有经典计算程序荷栽响应计算结果的比较，验证了所建立的离散元模型．以该离散元模型为基础，在沥青混凝土结构层的底部，采用尺度较小的离散单元描述粗集料的体积含量、分布特征以及空隙大小等细观结构，以此建立路面结构的多尺度模型．对路面结构宏观响应与细观结构的荷载响应进行了比较分析，并分析了沥青砂浆劲度对细观结构处荷载响应的影响．结果表明：粗集料与沥青砂浆界面位置的拉应力均值和离散系数均大于沥青砂浆内部；荷载引起的应力和应变在沥青砂浆内部和界面内部均存在不均匀分布；沥青砂浆的劲度越大，沥青混凝土内部的荷载响应分布越趋于均匀．

Dynamic response of multi-scale structure in flexible pavement to moving load

In order to study the dynamic responses in the microstructures of the pavement structure, the multi-scale modeling subjected to moving load is analyzed using the discrete element method （DEM）. The macro-scale discrete element model of the flexible pavement structure is established. The stress and strain at the bottom of the asphalt concrete layer under moving load are calculated. The DEM model is validated through comparison between DEM predictions and the results from the classical program. Based on the validated macro-scale DEM model, the distribution and the volumetric fraction of coarse aggregate, mastics and air voids at the bottom of the asphalt layer are modeled, and then the multi-scale model is constructed. The dynamic response in the microstructures of the multi-scale model are calculated and compared with the results from the macro model. The influence of mastic stiffness on the distribution of dynamic response in the microstructures is also analyzed. Results show that the average values and the variation coefficient of the tensile stress at the aggregate-mastic interface are far more than those within the mastics. The dynamic response including stress and strain distributes non-uniformly in both mastics and the interface. An increase in mastic stiffness tends to a uniform distribution of tensile stress in asphalt concrete.