基于精细化DEM建模的冷再生混合料断裂性能分析

冷再生沥青混合料包含水泥、乳化沥青、旧料等成分，具有材料组成复杂、界面结构多变的特点，其对冷再生混合料的抗裂性能具有显着影响。以冷再生沥青混合料的断裂性能为研究对象，提出一种精细化的数值建模方法，该方法包括细观结构特征精细重构和力学参数精确获取。采用彩色乳化沥青区分材料内部真实组成结构，并经过图像处理和MATLAB程序处理导入离散元（DEM）数值仿真软件中，进行冷再生混合料结构精细化重构；结合SEM原位力学测试方法获取考虑试件尺寸和加载速率影响的沥青砂浆精确力学参数，建立精细化的离散元数值仿真模型；基于精细化建模开展冷再生沥青混合料断裂性能和关键失效机理分析，并通过室内试验进行验证。数值仿真和室内试验结果表明：基于细观结构精细化重构和材料参数精确获取的离散元建模方法可以有效模拟分析冷再生沥青混合料的断裂性能；冷再生混合料的整体断裂特性属于脆性断裂，抗拉强度低的冷再生沥青砂浆是混合料内部的薄弱区域，混合料内部主要断裂界面为冷再生沥青砂浆-骨料界面。提高沥青砂浆黏聚强度和材料内部界面强度可以显著改善冷再生沥青混合料的抗裂性能。

Fracture Performance Analysis of Cold-recycled Mixture Based on DEM Precise Modeling

A cold-recycled asphalt mixture contains cement, asphalt emulsion, reclaimed asphalt pavement (RAP), and other components, which have the characteristics of complex material composition and changeable interface structure. This has a significant impact on the crack resistance of cold recycled materials. Therefore, this study considers the fracture performance of a cold-recycled asphalt mixture as the research object and proposes a refined numerical modeling method that includes fine reconstruction of meso-structure features and precise acquisition of mechanical parameters. The color emulsified asphalt was used to identify the true composition structure of the cold-recycled mixture, and the image was captured, processed, and imported into the discrete element method (DEM) numerical software using MATLAB program for the fine structure reconstruction of the cold-recycled mixture. Combined with the in situ SEM mechanical test method, the precise mechanical parameters of asphalt mortar were acquired, which considered the sample sizes and loading rates. Then, a refined discrete element numerical model was established, and the crack resistance and key failure mechanism of the cold-recycled asphalt mixture were studied, which was verified by laboratory tests. Numerical simulation and laboratory test results show that the discrete element modeling method based on refined meso-structure reconstruction and accurate parameter acquisition can effectively simulate the crack resistance of cold-recycled mixtures. The overall fracture performance of cold-recycled materials is brittle, and the tensile strength of the cold-recycled asphalt mortar is low, which is a weak area inside the mixture. The main fracture interface is between the cold recycled asphalt mortar and the aggregate. Therefore, improving the cohesive strength of asphalt mortar and the internal interface strength can significantly improve the crack resistance of cold-recycled asphalt mixtures.