基于数字散斑方法的OGFC混合料低温变形破坏行为研究

Study on Low Temperature Deformation and Failure Behavior of OGFC Asphalt Mixture Based on the Digital Speckle Method

目的研究四点加载状态下OGFC沥青混合料的低温变形破坏行为,提出基于弹性变形的应力重构,探究其变形过程中的应力变化规律。方法通过数字散斑方法结合四点弯曲试验,分析小梁试件完全破坏前应变场分布规律,并量化分析应变集中带区域应变变化规律。结果水平应变场随加载由均匀分布向应变集中带状区域渐变,具有局部化特征;通过关注点的点应变非线性增长曲线得到其起裂时间点、起裂应变以及变形时间段;基于DSM的应力重构可用于分析OGFC混合料变形阶段应力变化规律。结论赋予材料属性的应力重构与数字散斑方法相结合使得OGFC沥青混合料的应力测量更具有真实性。

In order to study the low-temperature deformation and failure behavior of OGFC asphalt mixture under four-point loading,the digital speckle method combined with four-point bending test is used to analyze the strain field distribution law and the strain change law in the strain concentration zone before the trabecular specimen is completely destroyed.The stress reconstruction based on elastic deformation is proposed to explore the law of stress changes in the process of deformation.The results show that the horizontal strain field gradually changes from a uniform distribution to a strain-concentrated banded area with the load,which has localized characteristics;the initiation time point,the crack initiation strain and the deformation time period are obtained through the non-linear growth curve of the point strain of the focus point;the DSM-based stress reconstruction can be used to analyze the stress change law of OGFC mixture in the deformation stage.The combination of stress reconstruction with material properties and digital scattering methods makes the stress measurement of OGFC asphalt mixes more realistic.