煤的变质程度、孔隙特征与渗透率关系的试验研究

以贵州六盘水矿区中高变质程度的原煤为对象，利用TESCAN VEGA II型自带能谱扫描电镜、ASAP2020型比表面微孔分析仪，对煤样的内外部孔隙特征进行研究；借助自主研制的三轴渗流装置，进行不同瓦斯压力条件下含瓦斯型煤的三轴渗流试验。结果表明：(1) 煤的变质程度与内外部孔隙特征呈正相关关系，变质程度越高，原煤的分形维数越高，原煤的吸附量和孔容也越大；(2) 原煤的内外部孔隙特征与渗透率呈正相关关系，内外部孔隙越发育，渗透率越大；(3) 在恒定平均有效应力和温度条件下，随瓦斯压力的增大，渗透率先急剧降低，而后降低趋势渐缓，且渗透率与瓦斯压力服从指数分布关系。研究结果对贵州六盘水矿区瓦斯灾害的防治和煤层气的开发利用具有一定的理论指导意义。

EXPERIMENTAL STUDY OF RELATIONSHIPS BETWEEN METAMORPHIC GRADE,PORE CHARACTERISTICS AND PERMEABILITY OF COAL

Internal and external pore characteristics of raw coal sample of medium and high degrees of metamorphism which were obtained from Liupanshui mining area were studied by using TESCAN VEGA II scanning electron microscope(SEM)-energy-dispersive X-ray(EDX) and ASAP2020 specific surface microanalyzer.Triaxial seepage experiments of constant different gas pressures were carried out by independently developed traixial seepage device.The results show that:(1) There is positive correlation between metamorphic grade of coal and interior and external pore characteristics.The higher the metamorphic grade is,the higher the fractal dimension is and the greater the raw coal adsorption capacity and pore volume are.(2) There is also positive correlation between internal and external pore characteristics of raw coal and permeability.The more developed the internal and external pore,the greater the permeability is.(3) Under the conditions of constant mean effective stress and temperature,with the increasing gas pressure,at first the permeability sharply decreases and then tends to decrease gradually;and the relationship between permeability and gas pressure obeys exponential distribution.The research results have some theoretical significance to gas disaster prevention and development and utilization of coalbed methane of Liupanshui mining area.