Experimental study on porosity and permeability characteristics of damaged coal in different shear end faces and confining pressures
ZHENG Chunshan;DONG Yangyang;XUE Sheng;JIANG Bingyou;ZHAO Yang
安徽理工大学 煤炭安全精准开采国家地方联合工程研究中心合肥综合性国家科学中心能源研究院(安徽省能源实验室)安徽理工大学 安全科学与工程学院
煤体损伤是影响渗透率变化和瓦斯流动的重要因素;采用多剪切端面损伤渗流测试系统和核磁共振仪,分析了不同剪切端面和围压下损伤煤体孔渗特性变化规律。结果表明:损伤煤体内中大孔增多,吸附空间向渗流空间转化,孔隙间连通性变好;50%剪切端面情况下,渗流空间(驰豫时间2>10 ms)平均面积百分比由9.89%增大为14.94%;剪切应力作用下,煤体轴向变形量不断增大,50%剪切端面比30%剪切端面导致的轴向变形量大,而围压值越大,轴向变形量越小;随着剪切应力的增大,煤体渗透率先降低后缓慢增加,当应力达到煤体强度阈值时,损伤煤体渗透率以指数形式增大,50%剪切端面对应的渗透率值普遍比30%剪切端面的大,前者是后者的7倍左右。
Coal damage is a significant factor which affects coal permeability changes and gas flow. Damage-based seepage testing system with multi-shear end faces and nuclear magnetic resonance instrument were adopted to analyze porosity and permeability characteristics of damaged coal in different shear end faces and confining pressures. It is found that the number of macro-pores in damaged coal increases. Meanwhile, adsorption space transforms into seepage space, with better connectivity between pores. In the case of 50% shear end face, average area percentage of seepage space (relaxation time2>10 ms) rises from 9.89% to 14.94%. Affected by shear stress, the axial deformation of coal continuously increases, 50% shear end face causing bigger axial deformation than the 30% shear end face. The larger the confining pressure value, the smaller the axial deformation. With increasing shear stress, permeability of coal decreases first before slowly growing. When stress reaches the threshold of coal strength, permeability of damaged coal rises exponentially. The permeability value corresponding to 50% shear face is generally larger than that of 30% shear face, and the former is about 7 times that of the latter.
gas drainage;damaged coal permeability;multiple shear end faces;porosity and permeability characteristics;confining pressure;gas flow
主办单位:煤炭科学研究总院有限公司 中国煤炭学会学术期刊工作委员会