基于图像技术的沥青混合料细观损伤演化研究

Research on Meso-damage Evolution of Asphalt Mixtures Based on Image Technology

借助于CT图像技术,以AC20、SMA16、ATB25混合料为试验研究对象,从细观角度对沥青混合料单轴压缩条件下的损伤演化规律进行了探讨。研究结果表明:在混合料损伤演化过程中,空隙对试件的变形起着控制作用;加载速度对内部裂纹的扩展速率和发育程度有重要的影响;温度对混合料的极限强度和裂纹扩展行为有显著影响;内部CT数等值线与外部同值等值线的连通可以作为启裂位置和损伤产生的判据。体应变为0的应力阶段所对应的损伤值可作为损伤门槛值,且损伤分维数与应力之间呈非线性关系,并随着损伤的演化发展逐渐增加。

By means of CT image technology, meso-damage evolution rules of three types of asphalt mixture specimens （including AC20, SMA16 and ATB25） under uniaxial compression were investigated, the results show that （1） voids in such a sample play the control role of deformation in the process of damage evolution; （2） propagation rate and growth degree of internal cracks are seriously influenced by loading rates; （3） temperature has significant influence on the ultimate strength and crack propagation behavior of asphalt mixtures; and （4） the penetration between isoline of internal CT values and external equivalent isoline could be regarded as the criterion for the start-split location and damage position. The damage value corresponding to the stress stage in which volumetric strain is zero could be taken as the damage threshold value, and the damage fraetal dimension, which has a nonlinear relationship with stress, develops gradually with the damage evolution.