Real-Time Visual Analysis of the Microcracking Behavior of Thermally Damaged Granite Under Uniaxial Loading

In high-temperature rock engineering projects, rocks are subjected to external loads. Studying the cracking behavior of thermally damaged rock under uniaxial loading is of great significance to engineering. In the present study, real-time computed tomography (CT) scanning was performed on thermally damaged granite subjected to compression loading to observe the evolution of spatial three-dimensional (3D) microcracks and planar two-dimensional (2D) microcracks. The porosity and crack length were further introduced to quantify microcracking behavior. The effects of the load on the 3D microcrack volume distribution and the length of 2D microcracks with different orientations were discussed. The results show that real-time CT imaging intuitively presents the evolutionary process of realistic microcrack morphology during loading. As the load level increases, the porosity of the specimen and the total length of 2D microcracks experience stages of slow decrease, slow increase, and rapid increase. The proportion of microcracks with larger volumes decreases and then increases as the load level increases. In the slice parallel to the loading direction, the length of microcracks within an angle range of 30 degrees-90 degrees to the loading direction decreases as the load level increases. In the slice perpendicular to the loading direction, the microcrack length distribution exhibits obvious anisotropy as the load level increases.