某高瓦斯矿煤岩渗透特性的实验研究

Experimental study on the permeability of coal rocks of an gas-rich coal mine

从某高瓦斯矿采集煤样,通过扫描电镜对其微结构和孔隙裂隙特征进行了观测。利用电液伺服岩石力学试验系统以数控瞬态渗透法进行了标准煤样全应力应变过程的电液伺服试验。根据实验结果计算出了煤样破坏过程中不同应变下的Darcy流渗透率、非Darcy流渗透率、非Darcy流β因子和加速度系数,给出了主应力差、煤样渗透率、非Darcy流β因子和加速度系数与轴向应变关系曲线,研究表明:该矿煤样结构均一,具有壳状断面和放射性细纹,有时可见稀疏裂隙;在煤样破坏过程中,由于围压的作用,全应力应变过程中煤样的渗透率随着应变的增大而发生变化;非Darcy流β因子和加速度系数趋势相同。

Coal samples are collected from a Gas-rich Coal Mine. The micro-structure and porous characteristics of the samples are observed by using scanning electronic microscope. Electro-hydraulic servo tests of standard coal samples under complete stress-strain process are conducted by using the electro-hydraulic servo controlled rock mechanics testing system and the numerically controlled transient permeability method. Based on the experimental results, the Darcy flow permeability, non-Darcy flow permeability, non-Darcy flow factor β, and acceleration coefficient are calculated for different strains during the course of destruction of the coal samples. These relationship curves are obtained： principal stress difference vs. axial strain, permeability vs. axial strain, non-Darcy flow β factor vs. axial strain, and acceleration coefficient vs. axial strain. The study shows that the structure of the coal samples is homogeneous, consisting mainly of crustiform section, and radiate pinstripe structures, with some micro-porosity and micro-fissure being seen; that because of the action of peripheral pressure, during the course of destruction of coal samples, the permeability under complete stress-strain process Changes as the strain increases, but does not change significantly; and that the non-Darcy flow factor β and acceleration coefficient have the same change tendency.