煤岩全应力-应变过程中渗透特性的研究

Study on permeability characteristics of coal rock in complete stress-strain process

选取安徽淮南张集矿的煤样,对加工成的9个标准试件(50 mm×H100 mm)进行全应力-应变过程中的渗透测试及CT扫描试验。渗透试验结果表明:煤岩的渗透率-应变曲线与应力-应变曲线具有相似的变化规律,且渗透率表现出应变滞后性,表明瓦斯在煤岩中的流动特性与受载过程中煤岩内部产生的损伤演化密切相关;围压使煤岩内部的瓦斯通道发生压密闭合,导致渗透率随围压的增大而减小。在渗透试验前后对试件进行CT扫描,结果表明,渗透试验前试件上基本观测不到有微观孔隙裂隙的存在,渗透试验后有明显的贯通裂缝产生,导致试件的渗透率在应力-应变峰后呈现急剧上升的趋势。

Nine standard coal samples with dimensions of 50 mm in diameter and 100 mm in height,which were taken from Zhangji Coal Mine in Huainan City of Anhui Province,and tested on gas flow regularities of complete stress-strain process and the X-ray industrial CT.The results of the permeability tests show that the permeability-strain curves are similar to stress-strain curves of the coal rock,and stress hysteretic nature is shown in permeability-strain curves,which indicates that the close relativity between the character of gas flow in the coal samples and the damage evolution of coal samples during the loading processes.The permeability is decreased with the developing of confining pressure which causes consolidation in the gas thoroughfare of coal samples.Tests by the X-ray industrial CT before and after the permeability tests show that there are rare micro-porosity and micro-fracture observed before the permeability tests,and clear cracks found after the permeability tests which indicate sharp rising of permeability after the peak of stress-strain curves.