CO₂吸附引起的结构变形对煤层稳定性有显著影响。利用自主研发的气-固耦合实验系统结合MTS力学试验系统，研究了CO₂吸附时间对煤体力学特性及力学参数变化规律的影响；通过工业CT扫描和三维重构技术构建了煤体裂隙结构模型，阐明了CO₂吸附时间对裂隙结构的影响，并利用COMSOL软件开展了CO₂在煤体中的流体动力学模拟，探讨了CO₂吸附作用下煤体裂隙扩展规律。结果表明：①不同CO₂吸附时间下煤体应力-应变曲线可分为3个阶段，受吸附时间影响显著，且峰值强度与弹性模量随吸附时间增加呈下降趋势，最大劣化幅度可达29.82%，劣化度呈上升趋势，但存在“时效性”，在5、7 d时劣化度幅度最大变化仅约0.5%；②受到CO₂吸附时间的影响煤体裂隙呈由外向内的扩展趋势，且先快后慢，煤体裂隙率及连通度在7 d时分别达到14.03%、1.59；③ CO₂在煤体内运移方向是由外向内，裂隙与基质间出现的应力集中区会造成裂隙发生扩展，使得煤体结构疏松化、抵抗荷载能力降低。

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.