盐蚀环境下沥青混合料多场耦合损伤演化机制

The damage evolution of asphalt mixture under the action of sulfate-water-temperature-ultraviolet (uv) radiation coupling effect is taken as the main line of research in this project. Through the self-designed multi-field coupling environment testing device, the road performance deterioration laws of asphalt mixture under multi-field coupling effect exposed to dry-wet/freeze-thaw cycles are investigated. On the aspect of macro appearance, the Logistic damage judgment model and multivariate Weibull statistic model based on the Damage and Reliability Theory are built. Through the X-ray CT（Computed Tomography）scanning technology and Fractal Theory, the void characteristic evolution law of asphalt mixture under multi-field coupling effect is set forth. Dynamic modulus and phase angle of asphalt mixture and asphalt mortar are measured through laboratory test, mesoscopic parameters of each phase medium of asphalt mixture are calculated and micromechanical models are built with finite element method. The SPT（Simple Performance Test）dynamic modulus test and IDT（Indirect Tension Test）are conducted for numerical simulation and the research on the compression and tensile damage mechanics behavior of asphalt mixture under multi-field coupling effect. Based on that, the interface adhesion failure mechanism between asphalt and aggregate, deformation as well as development and extension laws of cracks in asphalt mixture are explained from the mesoscopic viewpoint, which reveals the damage evolution mechanism of asphalt mixture exposed to multi-field coupling effect under the sulfate erosion environment. The research results can provide important theoretical foundation for improving the durability of asphalt pavement and pavement material design method in sulfate enrichment areas.

本项目以硫酸盐-水-温-紫外线多场耦合作用下沥青混合料损伤演化为主线，采用自行设计的多场耦合环境箱测试装置，研究干湿/冻融循环条件下沥青混合料多场耦合路用性能劣化规律；在宏观表象层次上构建沥青混合料的Logistic损伤判断模型和基于损伤与可靠度理论的多元Weibull统计模型；采用X-ray CT扫描技术与分形理论，阐明沥青混合料在多场耦合作用下空隙特征的演化规律；实测沥青胶浆与沥青混合料的动态模量和相位角，推算出沥青混合料中各相介质的细观参数，基于有限元法构建沥青混合料的细观模型；开展SPT动态模量试验与IDT间接拉伸试验的数值模拟，研究压缩与拉伸状态下沥青混合料多场耦合损伤力学行为，在细观层次上探明集料/沥青界面粘结失效机理、沥青混合料产生变形及裂纹发育延展规律，揭示盐蚀环境下沥青混合料多场耦合损伤演化机制。研究成果为提高富盐地区沥青路面耐久性及完善路面材料设计方法提供重要理论依据。

盐蚀环境对沥青路面耐久性劣化作用具有普遍性和直接性。本项目以硫酸盐-水-温-紫外线多场耦合作用下沥青混合料损伤演化为主线，采用自行研制的沥青混合料动水-盐蚀冲刷试验仪与改进的多场耦合环境箱测试装置，研究了掺盐（内掺与外掺）沥青胶浆多场耦合性能变化规律及干湿/冻融循环条件下沥青混合料多场耦合路用性能劣化规律；在宏观表象层次上构建了沥青混合料的Logistic损伤判断模型。借助SEM与红外光谱、X-ray CT扫描技术与分形理论等，深入探究沥青混合料在多场耦合作用下空隙特征演化规律及其损伤演化机制。研究结果表明：（1）盐分掺入使沥青表面自由能和极性分量降低，色散分量增加，沥青粘聚性降低，沥青与集料之间粘附性变差；（2）盐分-沥青界面呈现出“盐老化”效应，仍以物理作用为主；（3）盐-水-温度-紫外耦合作用下，基质沥青处于无粘韧性状态；（4）随盐溶液浓度增大，沥青混合料路用性能损伤程度亦随之增大; 相较于盐水浸泡环境，干湿循环条件下沥青混合料的强度损失大大增加，硫酸盐劣化效果显著；（5）盐溶液渗入沥青混合料空隙和裂缝中发生的结晶型侵蚀是导致沥青混合料性能劣化的主要诱因；（6）构建出的Logistic 模型能较好反映出沥青混合料耐久性变化规律（相关系数达0.97）；（7）提出了基于CT“sobel边缘检测法”的沥青混合料空隙率计算值修正方法，且精度较高；（8）采用局部CT值大津法对图像空隙/沥青胶浆界面进行分割，计算得到分割阈值T=532HU；（9）运用三维重构软件（MIMICS）对沥青混合料CT图像进行三维重构，揭示出多因素耦合作用下沥青混合料空隙特征（空隙率、空隙个数、分形维数等）演化规律；（10）对构建的三维数值试件进行间接拉伸试验，验证了模型的合理性。研究成果为提高富盐地区沥青路面耐久性及完善路面材料设计方法提供重要理论依据。