为揭示深部煤层注入CO₂过程中，超临界CO₂对无烟煤力学强度与微观结构的影响规律，以无烟煤为研究对象，对2种恒定温度（40、60 ℃）条件下超临界CO₂对煤体劣化特性进行探究，利用自主研制的超临界CO₂浸泡设备搭配煤体单轴加载装置对其力学强度进行初步测定，借助CT扫描系统表征孔裂隙等结构，通过分析不同浸泡时间（0、1、3、5、7 d）对孔裂隙的物化效应，揭示超临界CO₂浸泡后无烟煤宏观强度损失与微观结构演变的内在联系。结果表明：超临界CO₂对无烟煤宏观强度的劣化具有一定的时间效应，伴随着浸泡时间的增加，劣化效应逐渐减弱，逐渐趋于某一定值，其劣化主要时期为浸泡0～5 d，同时破坏模式改变，破坏颗粒的平均尺寸逐渐增大。同比恒温60 ℃，恒温40 ℃状态下的超临界CO₂对煤体劣化作用较为明显；借助CT 扫描系统发现，经超临界CO₂浸泡后白色矿物质消失，“溶蚀孔洞”逐渐扩大，新生孔裂纹不断发育，裂隙开度增加。煤样内部孔裂隙在0～5 d迅速发育成较为连续的孔隙团，此后内部孔裂隙缓慢发育，逐渐趋于稳定；超临界CO₂侵入煤体内部，其通过萃取煤基质中的有机物与溶蚀碳酸盐矿物组分，形成“溶蚀孔洞”，破坏晶体结构，导致内部孔隙团逐渐发育。伴随着比表面积的增大，煤体吸附能力增加，其“溶胀效应”进一步增加孔裂隙发育，最终导致宏观力学强度的改变；由宏观强度损失数学模型分析得到，煤体经过超临界CO₂浸泡后，强度包络线向右偏移，摩尔应力圆向左偏移，内摩擦角与黏聚力均变小，最终导致煤体宏观强度的损失。

In order to reveal the effect of supercritical carbon dioxide on the mechanical strength and microstructure of anthracite in the process of CO₂ injection into deep coal seams, takes anthracite as the research object, the degradation characteristics of coal by supercritical carbon dioxide under two constant temperatures (40 ℃ and 60 ℃) were investigated. The self-developed supercritical carbon dioxide immersion equipment combined with coal uniaxial loading device was used to preliminarily determine its mechanical strength. The structures such as pores and cracks were characterized by CT scanning system, and the physicochemical effects of different soaking days (0, 1, 3, 5, 7 d) on pores and cracks were analyzed. The intrinsic relationship between macroscopic strength loss and microstructure evolution of anthracite after supercritical carbon dioxide immersion was revealed. The results show that supercritical carbon dioxide has a certain time effect on the deterioration of the macroscopic strength of anthracite. With the increase of soaking time, the deterioration effect gradually weakens and gradually reaches a certain value. The main period of the deterioration is within 0−5 days of soaking, and the average size of the damaged particles gradually increases with the change of failure mode. Compared with the constant temperature of 60 ℃, the supercritical carbon dioxide under constant temperature of 40 ℃ has a more obvious degradation effect on coal. With the help of CT scanning system, it was found that after the supercritical carbon dioxide immersion, the white minerals disappeared, the “solution holes” gradually expanded, the cracks in the new holes continued to develop, and the crack opening increased. The internal pore and fissure of the coal sample developed rapidly into a relatively continuous pore group within 0−5 days, and then the internal pore and fissure developed slowly and gradually became stable. The supercritical carbon dioxide intrudes into the coal, and by extracting organic matter in the coal matrix and dissolution of carbonate mineral components, it forms “dissolution pores”, destroys the crystal structure, and leads to the gradual development of internal pore groups. With the increase of specific surface area, the adsorption capacity of coal increases, and the“swelling effect”further increases the development of pore and fracture, and finally leads to the change of macroscopic mechanical strength. According to the analysis of the macroscopic strength loss mathematical model, after the coal is soaked in supercritical CO₂, the strength envelope shifts to the right, the molar stress circle shifts to the left, and the internal friction Angle and cohesion become smaller, resulting in the macroscopic strength loss of the coal.