中文摘要：

利用微焦点工业CT对混凝土试件单轴压缩过程分阶段进行原位扫描，获得相应的系列CT图像。由数字体散斑法（Digital Volumetric Speckle Photography，DVSP）获得了试件内部三维位移场与应变场。混凝土内部非均匀细观结构可以作为散斑结构成为变形信息的载体用于试件内部变形的测量；通过位移场和应变场的分析，揭示了试件内部变形局部化区域的演化及破坏过程，局部化区域与试件最终破坏面位置相一致。根据试件的体积应变随轴向应力的变化曲线分别定义了小于CT尺度微裂隙和CT尺度裂隙的发育点，分别为峰值应力的54．7％和82．0％，这两点同时对应着试件扩容的起始点及塑性变形的起始点。结果表明，DVSP与CT技术相结合能够直观地揭示混凝土试件内部变形局部化产生及发展过程，为三维变形的精细测量及可视化提供了方法。

英文摘要：

A concrete specimen under uniaxial Computed Tomography （ICT） in situ, from which compression was scanned by using Micro-focus Industrial sequence CT images of the specimen under different loading levels were acquired. With application of Digital Volumetric Speckle Photography （DVSP）, 3D displacement fields and strain fields in the specimen were calculated. The heterogeneous meso-structures in the concrete specimen can be seen as speckle patterns which are the deformation information carriers. From the displacement fields and strain fields analysis, deformation localization evolution and damage process are indicated, and the localization zone is consistent with the final position of failure in the specimen. Onset points of the micro-crack under CT resolution and the crack above CT resolution in the specimen are defined in the volumetric strain-axial stress curve, and the corresponding stresses of two points are 54.7% and 82.0% of peak loading, respectively. These two points also correspond to the onset points of dilatancy and plastic deformation, respectively. The results demonstrate that DVSP technique combined with CT can be applied to revealing the onset and development of deformation localization, and can be used for accurate measurement and visualization of 3D deformation.