盐侵蚀-冻融耦合作用下沥青混合料的三维动态渐进劣化行为

The problem of deicer-frost scaling for pavement becomes increasingly serious in China, and it has been a problem that is exigent to be solved. However, the mechanism of deterioration has not been explained clearly. This project will focus on the progressive deterioration behaviors of asphalt mixture under coupling effect of salt scaling and freeze-thaw. The X-ray CT will be used to scan the asphalt mixture specimens, the algorithm of the reconstruction for asphalt mixture will be optimized, and the internal structure of asphalt mixture will be identified exactly. Consequently, the digital specimen which reflects the real microstructure of asphalt mixture will be reconstructed. The TDR (Time Domain Reflectometry) will be utilized to detect the process and the status of deicer-frost scaling, the migration of the salt solutions in the air voids will be characterized exactly. On this basis,, the numerical simulation of the automatic growth for the cracks will be performed, which is incorporated with the EFEM (Extended Finite Element). The real-time freezing pressure data will be measured as the input-parameter for the simulation, the cracking process will verified with the X-ray CT scanning, and then the deicer-frost scaling process in the internal asphalt mixture will be represented vividly with the 3D visualization method. The internal deicer-frost scaling of asphalt mixture will be explored from a new angle of the view. The project will establish a new framework to investigate the mechanism of deicer-frost scaling for the pavement.The work aims at solving one of fundamental issues for the deicer-frost scaling, it will provide the scientific evidence for the setting of the future specification suited to country's actual conditions in China.

沥青路面盐冻问题在中国日益突出，已成为一个亟待解决的问题，但其破坏机制尚未阐明。本课题拟以盐侵蚀-冻融耦合作用下沥青混合料内部的渐进劣化行为作为切入点，利用X-ray CT扫描沥青混合料试件，优化现有混合料CT图像重构算法，精确识别混合料内部结构特征，建立基于沥青混合料内部真实细观分布的数值试样；借助时域反射技术手段，实时监测混合料内部的盐冻程度和盐冻状态，准确表征盐溶液在空隙内的迁移特征，在此基础上，利用最新发展的扩展有限元方法，结合时域反射同步监测的动态冰压值，实现裂纹的全自动扩展数值模拟，并利用X-ray CT无损扫描同步验证，进而以三维可视化方式生动呈现沥青混合料内部盐冻渐进劣化过程，从新的视角探究封闭混合料内部三维动态渐进劣化行为，构建一种全新的沥青路面盐冻机理研究模式，以期解决沥青路面盐冻机制当中的一个基础问题，为将来制定适合中国国情的沥青路面盐冻规范提供科学依据。

沥青路面盐冻问题在中国日益突出，已成为一个亟待解决的问题。我们采用X-ray CT扫描沥青混合料试件，并对获取的CT 图像进行了分析，根据初步处理后的CT图像，研究了数字图像处理技术中的空隙精确识别算法，对图像进行了三维重构，着重对现有三维重构算法进行了改进，构建了三维数值模型，在盐侵蚀环境下，对沥青混合料进行了冻融循环试验，并对盐冻进程进行了实时监测，结合监测的冰压数据和重构数值模型，预期将进行扩展有限元数值模拟，研究裂纹的扩展演化行为，对获得的各种盐冻特征指标进行分析，获得了一系列研究成果，本项目的研究从细观视角揭示封闭混合料内部的盐冻破坏规律，为有效控制沥青混合料盐冻破坏奠定理论和技术基础。