含不同气体煤岩全应力-应变渗透特性试验研究

Experimental Study on Permeability of Coal during the Complete Stress-Strain Process with Different Gases

分别以吸附性气体甲烷(CH4)、二氧化碳(CO2)和"非吸附性"气体氦气(He)为渗流介质,在三轴伺服渗流装置上进行了含不同气体煤岩全应力-应变加载过程煤岩渗透特性的研究。试验结果表明:三种气体的渗透率-应变曲线变化趋势相近,其相对应力-应变曲线变化有明显滞后性,吸附性气体的滞后性表现较为明显;在弹性到屈服点阶段和应变软化阶段,煤样渗透率与有效应力呈负指数关系;煤样对不同吸附能力的气体,其渗透率之间存在明显差异性;对煤样进行饱和吸附后,二氧化碳和甲烷所测渗透率较之氦气测得的(视为煤样绝对渗透率)平均减小了55%,且二氧化碳所测渗透率小于甲烷。

The permeability research of coal during the complete stress-strain process is carried out on the 3-axis servo seepage device using adsorptive gas （ CH4, CO2 ） and non-adsorptive gas （ He ） as the seepage medium. The test resuh shows that the seepage rate-strain curves of three kinds of gas are close to each other. Comparatively, the relative stress-strain curve changed slowly, especially for the adsorptive gas. Up to yield point in the elastic stage and at the strain softening stage, permeability and effective stress have a negative exponential relationship. For different adsorptive gas the coal seepage rate is different. In case of coal sample saturated with adsorptive gases, it is found that the seepage rate of CO2 and CH4 is decreased by 55% in average and the seepage rate of CO2 is less than that of CH4.