超临界CO₂压裂技术作为极具发展潜力的压裂煤体增透瓦斯技术，明晰其对煤体的影响机制，有助于推动该技术的机理研究和实践工程应用。为准确表征超临界CO₂作用下高阶煤的孔裂隙结构及力学特性变化，以焦煤集团中马村矿的高阶煤为试验对象，通过自主搭建的超临界CO₂浸泡试验系统，结合全自动物理吸附仪（BET）以及全自动压汞仪（MIP），对超临界CO₂处理前后高阶煤的孔裂隙结构变化进行分析，并利用单轴压缩和声发射试验系统对超临界CO₂处理前后高阶煤的单轴压缩力学特性和声发射特征进行测定。结果表明：超临界CO₂对高阶煤具有良好的扩孔增渗作用。超临界CO₂处理后高阶煤的微小孔孔容占比降低，中大孔孔容占比增大，且高阶煤的总孔容增大；超临界CO₂对高阶煤的力学特性具有明显的劣化作用。超临界CO₂处理后高阶煤单轴抗压强度和弹性模量均显著下降，降幅分别为70.06%和55.56%，且超临界CO₂处理后高阶煤的内部声发射信号活跃度明显下降，高阶煤单轴抗压时间、累计振铃计数以及累计能量分别降低了98.68 s、95.14×10³个、200.30 V·ms，降幅分别为46.65%、37.65%、50.03%，高阶煤累计振铃计数以及累计能量平静期占比均显著增加，缓增期占比均降低，激增期前者占比降低，后者占比小幅度增加。研究成果将有助于推动超临界CO₂压裂技术的机理研究，对深部高阶煤的煤层气开采和CO₂地下封存具有一定指导意义。

The supercritical CO₂ fracturing technology has significant potential for developing coal fracture and increasing gas permeability. Understanding its influence mechanism on coal is crucial for advancing research and practical engineering applications of this technology. In order to accurately characterize the changes of pore-fracture structures and mechanical properties of the high-rank coal under the action of supercritical CO₂, taking high-rank coal from Zhongmacun Mine of Coking Coal Group as the experimental object, the changes of pore and fracture structure of the high-rank coal before and after supercritical CO₂ treatment were analyzed by Brunauer-Emmet-Teller (BET) and Mercury intrusion porosimetry (MIP), and the mechanical and acoustic emission characteristics of the high-rank coal before and after supercritical CO₂ treatment were tested by combining with uniaxial compression and acoustic emission experimental system. The results show that supercritical CO₂ had a good effect on pore expansion and permeability enhancement of the high-rank coal. After supercritical CO₂ treatment, the percentage of micro-small pore volume of the high-rank coal decreased, the percentage of medium and large pore volume increased, and the total pore volume of the high-rank coal increased after supercritical CO₂ treatment. Supercritical CO₂ had an obvious deteriorating effect on the mechanical properties of the high-rank coal. The uniaxial compressive strength and modulus of elasticity of the high-rank coal after supercritical CO₂ treatment were significantly decreased by 70.06% and 55.56%, respectively. The acoustic emission signal activity of the high-rank coal after supercritical CO₂ treatment decreased significantly, and the uniaxial compressive time, cumulative ring counts and cumulative energy of the high-rank coal were reduced by 98.68 s, 95.14×10³, and 200.30 V·ms, with the decreases of 46.65%, 37.65%, and 50.03%, respectively. The proportion of accumulated ringing count and accumulated energy in the quiet period of high rank coal increased significantly, while the proportion in the slow period decreased. The proportion in the surge period of accumulated ringing count decreased, while the proportion of accumulated energy increased slightly. The research results will be conducive to promoting the mechanism research, and have certain guiding significance for the coalbed methane extraction of deep high-rank coal and CO₂ underground storage.