为了掌握三向应力条件下煤体渗透率的变化规律,基于捆绑的火柴棍模型,采用弹性理论分析了煤体基质和裂隙变形对渗透率的影响,建立了两种三向应力条件下煤体渗透率的动态演化模型——指数型和立方型,两种模型均突破以往较多模型采用的单轴应变假设,考虑了三向受力条件下煤体的横向应变不为0以及轴向荷载增加的情况。在分别改变轴压围压组合值、气体压力条件下,将理论模型与室内试验结果进行对比分析,结果表明:煤体渗透率随着载荷水平的升高而减小、随着气体压力的升高而增大;两种条件下指数型渗透率模型对煤体渗透率演化过程的定量描述均优于立方型。

In order to study the coal permeability under three-dimensional stress condition,the permeability model of exponential form and cubic form were established. The two forms of permeability model were based on bundled match- stick concept. Meanwhile,the influence of matrix and fissure deformation of coal on permeability was analyzed by using the elastic theory. The two forms of model break through the uniaxial strain assumption and contain the fact that the transverse strain is not zero and the axial load is increased under three-dimensional stress condition. Under the condi- tions of changing axial pressure,confining pressure and gas pressure respectively,the theoretical model and laboratory test results were compared and analyzed. The results show that the coal permeability decreases with the increase of load level and the permeability increases with the increase of gas pressure. Under the two conditions,the coal permeability model of exponential form is better than the cubic form in the quantitative description of permeability evolution. The re- sults are of significance to the study of gas migration and extraction.