The triaxial compression tests of raw coal under different confining pressures were carried out by the industrial CT scanning system of coal and rock under load to investigate the mechanical properties and damage characteristics of raw coal under different confining pressures, the CT scanning information of the whole process of destabilization and damage of raw coal was obtained by combining with its own CT scanning system, and the evolution law of crack propagation of raw coal under different confining pressures was analyzed. The results show that: (1) With the increase of confining pressure, the overall bias stress-strain curve shifts to the right, the peak strength increases linearly, while the peak strain and elastic modulus both increase as a quadratic function, and the peak strength increases by the largest amount; (2) Based on the CT scan images, the fracture evolution characteristics inside the coal sample can be divided into four stages: fracture pressure density slowly decreasing stage, fracture sprouting stable development stage, fracture rapid increase stage, fracture expansion through stage, and with the increase of confining pressure, the fracture density gradually decreases; (3) Under triaxial loading, the damage of raw coal is mainly in the form of shear damage, with the size of the breaking angle ranging from 20° to 40°, and with the increase of confining pressure, the breaking angle increases as a quadratic function. The research results have certain reference significance for underground roadway, stope support design, surrounding rock stability judgment and mine disaster and accident prevention.

The structural deformation caused by CO₂ adsorption has a significant effect on the stability of coal seam. The authors studied the effect of CO₂ adsorption time on the mechanical properties of coal and analyzed the variation of mechanical parameters of coal with adsorption time by using the gas-solid coupling test system and the MTS mechanical test system. By using the industrial CT scanning system and 3D reconstruction technology, the authors built a coal crack structure model to clarify the influence of CO₂ adsorption time on the crack structure. Through data interaction with the COMSOL simulation software, the authors carried out the fluid dynamics simulation of CO₂ in coal to discuss the influence of CO₂ adsorption on the crack propagation law of coal. The results show that: ① The stress-strain curves of coal under different CO₂ adsorption time can be divided into three stages, with each stage significantly influenced by the adsorption time. Both the peak strength and elastic modulus exhibit a decreasing trend as the adsorption time increases, with a maximum reduction up to 29.82%. The degree of deterioration increases correspondingly but shows a time-dependent characteristic. Between 5 and 7 days, the change in the deterioration effect is only about 0.5%, indicating a stabilization trend over time. ② The CT scan results show that the cracks in coal propagate from the outside to the inside, and this trend is influenced by the CO₂ adsorption time, exhibiting a pattern of initially rapid change followed by slower change. At 7 days, the cracking rate and coalescence rate of coal reach 14.03% and 1.59, respectively, indicating that CO₂ has a certain damaging effect on the coal structure. ③ The authors carried out migration modeling for CO₂ on the representative volume element (REV) of coal. The results show CO₂ migrates in coal from the outside to the inside, and there is a stress concentration area between the crack and the matrix, which causes the crack to propagate, resulting in loosened coal structure and reduced load resistance.