关键词: 数字图像相关, CT扫描, 颗粒流程序, 单轴压缩, 裂纹扩展

Abstract: Circular hole and fissure are common flaws in rock mass; and their crack inoculation and evolution mechanisms have become one of the most important research subjects in the field of rock mechanics. Rock-like specimen containing circular hole and fissures are constructed and subjected to uniaxial compression based on digital image correlation(DIC) technology, computed tomography(CT) scanning technology, acoustic emission(AE) monitoring technology and particle flow code in PFC2D calculation data. Under the interaction between circular hole and fissures, the mechanical characteristics such as strength and deformation and fracture development are investigated in detail. Research results show that: (1) the number of acoustic emission events are relatively small and uniform in pre-peak; but the number of acoustic emission events are large in post-peak; and the greater the absolute value of the stiffness at the time of stress drop, the greater the frequency of acoustic emission events. (2) The macroscopic cracks generated by specimen failure can be classified into two modes, namely mode Ⅰ (tensile crack) and mode Ⅱ (shear crack). The mode Ⅰ crack first initiates from the ends of the fissures and the upper and lower of the circular hole, which is approximately parallel to the loading direction. The mode Ⅱ crack, extending at a certain angle with the loading direction, mainly occurs in the rock bridge area between the circular hole and the inner side of the fissures, and the area between the outer side of the fissures and the boundary of the specimen. (3) There are mainly two kinds of crack propagation paths, i.e. airfoil tensile crack propagation and secondary coplanar crack propagation. Among them, the main crack propagation is the airfoil tensile crack in the early loading stage, and the secondary coplanar crack growth is the main one in the late loading stage. (4) The DIC technology, CT scan technology, AE monitoring technology and PFC2D calculation method are adopted synthetically, which can establish the relationship between mesomechanical mechanisms and macromechanical response in the process of rock mass destruction and reveal the development and distribution characteristics of surface and internal fractures in rock masses intuitively and accurately.

Key words: digital image correlation, CT scanning, particle flow code(PFC), uniaxial compression, crack propagation