多尺度域下沥青材料水分-荷载耦合作用损伤机制及统一模型

The long-term action of moistrure as one of the most importatant environmenal factor and the influence of interfacial & structural characteristics in micro and meso level respectively were not considered into the traditional pavement mechanical analysis,which is based on the classic continuum medium concept. Firstly, using microscopic observation techniques and mass diffusion principle, damage rules of the contact interface between aggregate and asphalt/mastic and mastic itself due to the water eroding will be analyzed. Furthermore, adhesive model for the interface and cohesive model for the asphalt/mastic could be established considering the influence of moisture. Secondly, X-ray computed tomography and digital image processing techniques are utilized to implement the mesoscopic mechanical model of asphalt mixture including the interfacial characteristics in micro-scale. Based on numerical simulations of asphalt mixtures under the coupled moisture-mechanical action in meso-scale, damage mechanism will be investigated. Thirdly, the macroscopic homogenous method including micro and meso damage characteristics of asphalt mixture could be conducted through the accomplishment of Representative Volume Element (RVE). Combining with the numerical analysis of the interaction between tire and pavement, macroscopic dynamic response of asphalt pavement subjected to the coupling action of moisture and traffic loading will be obtained. Finally, in multi-scale domain, the unified damage mechanical model of apshalt material could be established,and moisture damage mechanical behavior and performance decay rules will be finally disscused for the asphalt material subject to the coupled moisture and loading action. This research could identify the damage mechanism of asphalt material due to the coupled moisture-mechanical action and its hereditary and variational relationship among different scales for its mechanical behavior, which could contribute to its optimization design and accurate performance prediction. It aslo supports the research about failure mechanism of pavement material.

针对连续介质路面力学分析中未考虑水分作为环境因素的长期作用以及沥青材料微观界面特性和细观结构特性的影响。首先，基于微观测试技术及质量扩散原理，研究动水作用下集料-沥青(胶浆)界面及胶浆本身损伤规律，建立考虑水分影响的界面粘附及粘聚模型；其次，基于CT 断层扫描及图像处理技术，建立考虑微观界面特性的混合料细观模型，研究细观尺度水-力耦合作用下沥青材料的损伤机制；而后，基于代表体积单元实现考虑微、细观损伤特性的宏观尺度材料均一化，结合胎-路交互作用数值模拟分析，揭示宏观尺度水分-荷载耦合作用下路面结构动力响应规律；最后，建立多尺度域下沥青材料水-力耦合作用统一损伤模型，探讨水分-荷载耦合作用下沥青材料水损伤力学行为及性能衰减规律。 本研究揭示沥青材料多尺度域下水-力耦合损伤机制及不同尺度间力学行为的遗传变异关系，为优化其材料组成和准确预估其路用性能提供依据，也为研究路面材料的破坏机理奠定基础。

自然环境中水分对沥青路面微观界面特性和细观结构损伤是不可忽略的。长期水分-荷载耦合作用下混合料宏观路用性能损伤与细微观乃至纳观结构损伤演化有着本质的内在联系。宏观路面水损害是由微观界面局部脱粘、界面粘结损伤累积、细观骨架及孔隙结构劣化而最终引起的。传统基于经验现象学的沥青材料水损害研究未考虑长期损伤的多尺度演化行为，无法从本质上解释材料水分损伤机理及结构力学行为，而难以为提高抗水损伤性能的沥青材料优化设计提供理论支持。因此，开展水分-荷载耦合作用下沥青路面材料多尺度域下损伤机制及尺度间力学行为的遗传变异关系研究，有助于深入理解材料水分损伤演化机理，预测材料损伤力学行为演化规律，从多尺度角度为耐久性材料优化设计提供理论支撑。. 为探究纳微观尺度水分子扩散行为及材料界面损伤机理，开展了沥青分子体系及沥青-矿物分子体系内水分子运动、扩散吸附、界面分子结构及近集料胶浆流变行为与粘结特性研究。为定量表征细观尺度水分作用下混合料骨架及孔隙分布特性及性能损伤演化，提出了混合料细观结构特性表征方法并建立了细观水分渗流及断裂损伤预测模型。为实现混合料细微观水损伤的宏观均一化，提出了局部等效代表体积单元的获取方法，并实现了移动荷载作用下饱和/非饱和粘弹性沥青路面结构动力响应解析求解及数值模拟预测。为建立多尺度域统一的沥青材料水损伤及性能预估模型，提出了冻融循环下路面结构加速加载试验方法并建立了路面结构性能衰减模型。研究结果表明，水分扩散行为对材料几何及外界湿度具有依赖性，界面水分扩散各向异性。水分作用下界面微观结构改变使得砂浆力学性质及砂浆断裂性能降低，细观非均匀的孔隙结构引起复杂孔隙渗流集中现象及渗流行为各向异性。均匀化的多孔介质饱和/非饱和路面结构动力解析解及移动荷载下结构动力模型表征了渗流及结构力学行为，基于路面结构监测信息的性能预估模型可预测实际服役环境沥青路面结构性能。