湿热环境下沥青路面剪切流变行为与模型研究

The shear rheology of asphalt mixture is one of the leading causes of asphalt pavement diseases, such as: rutting. Currently, the formation mechanisms of pavement shear-type diseases were mainly studied based on the couple of temperature and load by using the continuous mechanics theory from the macroscopic level and the studies in the meso-scopic level are not enough. Furthermore, Scarcely had the research findings about the shear performance degradation causing by water (wet environment) been published. So it has important theoretical meaning that the researches on shearing rheology behaviors and meso-scopic damage mechanism of asphalt mixture use the discontinuous mechanics method from meso-scopic level in the wet and hot environment. The relative researches will be developed using Asphalt Pavement Analyzer(APA) and industrial CT Scanner in the wet and hot environment in the project. Firstly, the asphalt migration and the feature of the coarse aggregate skeleton meso-structure characteristics of mixture shear deformation are obtained. The appropriate gradation design method and gradation evaluation parameters will be put forward according to the above research. Secondly, the relations of macro-scopic deformation characteristics and meso-scopic rheological characteristics of asphalt mixture will be discussed by researching the meso- scopic level shear rheological characteristics, digital images, and shear parameters by simulating the asphalt typical migration. Finally, the damage models of asphalt mixture shear rheology in the meso-structural level and asphalt migration are built based on the discrete element method, mixture digital image, and mechanic parameters. Moreover the meso-structural shear rheology mechanics of asphalt mixture will be analyzed theoretically by means of numerical simulation research. Thus the goals which explain the failure mechanism of shear-type disease of asphalt pavement are achieved. According to those research results, the approaches including pavement structural design method and material design method which alleviate shear-type disease of asphalt pavement are put forward. It can provide a serial of theoretical and technical supports for the designs of structure and material of high performance asphalt pavement in the wet and hot environment.

沥青混合料剪切流变是引发沥青路面车辙、推移等病害的主要原因之一，当前主要是采用连续力学研究温度与荷载耦合下路面剪切病害形成机理，但在细观方面研究较少，且鲜见有关于水(湿环境)导致沥青混合料抗剪性能劣化的成果，因此探索采用离散元从细观层面研究湿热环境下沥青混合料剪切流变行为和损伤机理具有重要的理论意义。 项目在湿热环境下采用APA路面分析仪和工业CT等开展相关研究，获取沥青迁移和沥青混合料剪切变形细观骨架特征，提出基于抗剪的级配设计方法和和级配评价参数；获取沥青混合料细观剪切流变图像特征和沥青典型迁移状态模拟试件的混合料抗剪性能参数，探索沥青混合料细宏观的联系；建立沥青迁移和混合料剪切流变细观损伤离散元模型，借助模型研究沥青混合料剪切流变损伤规律，揭示沥青路面剪切型病害的破坏机理，提出缓解湿热环境下路面剪切型病害的结构与材料设计方法。为湿热环境高性能路面结构和材料设计提供技术支撑。

在湿热环境下，沥青路面剪切型破坏（如车辙）问题尤为突出，造成了巨大的经济损失和不良社会影响。针对沥青路面剪切型破坏，国内外学者进行了大量的研究探讨，但目前已有研究成果主要针对高温重载等条件下的沥青路面的剪切变形（车辙），鲜见湿、热、荷载耦合下的沥青路面剪切破坏行为研究。而自离散元法和数字图像技术应用到沥青路面细、微观研究中以来，研究主要集中在沥青混合料的裂缝、疲劳性能等方面，在沥青混合料的剪切流变行为研究仍较薄弱。因此，本项目采用宏观与细观相结合、试验与理论相结合的研究方法，在沥青路面调研的基础上，研究了湿热环境下沥青迁移规律与沥青混合料剪切变形的细观结构特征，分析了各个因素对剪切流变的影响程度为：温度>湿度>荷载>加载速度。根据剪切流变试验中的沥青混合料迁移情况，进一步分析了其对沥青混合料力学性能的影响，发现随着沥青迁移量的增大，沥青混合料动态模量E*和动态模量组合参数E*/sinφ呈逐渐减小的趋势，抗永久变形能力明显减弱。同时，基于离散元法构建了沥青混合料剪切流变模型，结合数字图像处理技术，从细观角度总结了沥青混合料在不同湿热环境下的剪切流变损伤规律和沥青迁移规律，并进一步探索了缓解湿热环境下沥青路面剪切型病害的结构与材料设计方法。项目研究成果对沥青混合料的设计和沥青路面车辙等剪切型病害防治措施的研究具有重要的理论指导意义和工程实用价值。