基于数字图像技术的沥青混合料反射裂纹扩展行为

为了研究不同加载模式下的沥青混合料反射裂纹扩展行为，对复合小梁试件进行复合型和弯拉型破坏荷载试验以及不同应力比状态的疲劳试验，并基于数字图像相关技术(digital image correlation, DIC)观测反射裂纹萌生至扩展全过程，从裂纹宽度、裂纹扩展路径、裂纹扩展高度及疲劳反射裂纹扩展速率深入分析其扩展行为。结果表明：沥青混合料反射裂纹扩展行为经历微裂纹萌生、微裂纹发展阶段、微裂纹向宏观裂缝转变、宏观裂缝快速发展4个阶段。反射裂纹扩展由主裂纹扩展以及次裂纹扩展构成，且次裂纹扩展速率高于主裂纹。采用logistic函数对混合料疲劳反射裂纹扩展量进行拟合是可靠的。研究成果对于完善沥青路面设计及其耐久性评价具有重要意义。

Research on Reflection Crack Propagation Behavior of Asphalt Mixture Based on DIC Technology

To study the reflection crack propagation behavior of asphalt mixture under different loading modes, composite and flexural failure load tests and fatigue tests under different stress ratios were carried out on composite trabecular specimens. The whole process of reflection crack initiation and propagation was observed based on digital image correlation technology (DIC). The crack propagation behavior was analyzed from crack width, crack propagation path, crack propagation height and fatigue reflection crack propagation rate. The results show that the reflected crack propagation behavior of asphalt mixture goes through four stages: microcrack initiation, microcrack development, microcrack transformation to macro crack, and macro crack rapid development. The reflected crack growth consists of primary crack growth and secondary crack growth, and the secondary crack growth rate is higher than that of the primary crack. It is reliable to use logistic function to fit the fatigue reflection crack propagation of the mixture. The research results of this paper are of great significance for improving asphalt pavement design and durability evaluation.