针对加载、卸载作用下煤体变形及渗透机制的复杂性,利用渗透-力学耦合特性测定仪,根据瞬态脉冲原理,在40℃下,研究了不同卸载状态时CH4在煤体中的渗透行为,并就卸载前后煤样红外光谱和透射电镜结果进行对比分析,从微观角度讨论了加卸载对渗透特性的影响及引起煤体微观结构的应力效应。研究结果表明:带围压试验的煤样渗透率均较低,卸载到设定值后渗透率增高,且有效围压越大,渗透率变化越大;在微观上,煤样的有效围压越大,红外光谱特征参数I2值越高,脂肪链变长且易断裂和脱落,裂隙结构面活性增强,煤体颗粒易于损伤而破裂,并呈现出颗粒多碎性和强度弱化区,对煤体微裂纹的萌生、扩展直至形成宏观裂纹起加剧作用,卸载后煤体渗透率增大。

According to the complexity about coal deformation and seepage mechanism caused by loading and unloading prccess, the paper used the coupling testi ng equipment of permeability-adsorption-mechanical with coal and transient pulse method, under the condition of 40。C, the penetration behavior of gas in the coal body under different unloading conditions was studied, and the result of experiment of FTIR spectroscopic and transmission electron microscope with unloading raw coal sam ples was comparatively analyzed, the permeability characteristic was affected and its causes the stress effect of microstructure by unloading confining pressure were di scussed from microcosmic.The results showed that the permeability of coal samples overall under-owned with the confining pressure, it rose after unloading, and the eff ective confining pressure was higher, the rate of permeability change was greater.At the micro level, with the increase of confining pressure, the value of spectrum char acteristic parameter 12 increased, aliphatic chain longer and easy to break or fall off, the activity of fissure structure surface enhanced, aliphatic content reduce, coal pa rticles were easy to damage and fracture, these were obviously intensify the micro crack initiation, propagation to form macroscopic crack, at last increased the permea bility of coal body.

国家自然科学基金资助项目(50974055,51204065)；河南省教育厅科学技术研究重点资助项目(13A440333)；