Abstract: Rock rupture refers to the process of crack initiation, propagation and coalescence. In order to study the dynamic propagation and evolution process of internal cracks in rock subjected to deformation and failure, industrial CT was used to conduct phased observation and scanning of the rock rupture process, and a three-dimensional rock fracture model was constructed by vectorization of CT image stack. The characteristic parameters of the crack structure were statistically analyzed to quantitatively characterize the crack propagation during the rock rupture process. On this basis, the local failure morphology characteristics on crack propagation path were extracted and the rock and mineral identification experiment was combined for meso-scale analysis. The research results show that the three-dimensional fracture propagation process can be quantified using parameters such as fracture volume V, surface area S, and fractal dimension D, and the parameters experience a change law of "basically unchanged–small increase–surge". Based on the CT slice images, the crack area can characterize the local crack propagation characteristics of the rock, and it corresponds to the expansion and evolution of the three-dimensional cracks at the same stage. The mesostructure of the rock has a great influence on the crack propagation, which form the extension around the gravel, through the gravel, and bifurcation when encountering gravels. The research results will provide a research foundation for rock instability failure and disaster warning of engineering rock mass.

Key words: computer tomography scan, crack evolution, 3D reconstruction, quantitative characterization, extension features