超临界CO2气爆致裂规律实验研究

针对我国低渗透性煤层增透困难的现状，研发了可控超临界二氧化碳气爆发生装 置，对不同强度的模拟煤体进行了不同温压条件下的超临界CO2气爆实验，结合孔内窥 镜观测和外观测量手段，对爆后宏观裂隙数目和长度等爆破响应信息进行统计分析。结 果表明:气爆裂纹起裂所需的最小爆破压力与介质的抗拉强度呈指数式增长的关系，主 要是固体材料在动力载荷作用下强度增大引起的；超临界二氧化碳气爆后产生宏观裂隙 的数目和累计长度与爆破压力满足Logistic函数关系，是裂隙面积超线性增加所消耗能 量也超线性增加的结果；超临界CO2对温压条件敏感，爆破有降温作用，是良好的物理 爆破原料，使用超临界二氧化碳作为爆破原料的爆破效果优于空气爆破效果。

Experimental study on laws of crack caused by gas burst of supercritical carbon dioxide

To change the current situation that it is difficult to increase the permeability of low permeability coal seam in China, a generating device on controllable gas burst of supercritical carbon dioxide was developed, and the gas burst experiments of supercritical carbon dioxide under different pressure and temperature conditions were conducted on simulated coal mass with different intensity. Combined the hole endoscope observation with appearance measurement means, the statistical analysis was carried out on the burst response information, such as macroscopic crack number and length after the burst. The results showed that the required minimum burst pressure for gas burst crack initiation presents an exponential growth with the tensile strength of media, which is mainly caused by the strength increase of solid material under the action of dynamic load. The number and cumulative length of macroscopic crack after gas burst of supercritical carbon dioxide meet the Logistic functional relationship with burst pressure, which is caused by the ultra-linear increase of energy consumption with the ultra-linear increase of crack area. Supercritical carbon dioxide is sensitive to temperature and pressure and the burst has a cooling effect, so it is a good physical burst material, and the effects of burst using supercritical carbon dioxide as burst material is better than that of air.