研究工作面前方煤岩体瓦斯渗透率分布对合理抽取瓦斯具有技术指导意义。通过简化孔隙、裂隙等效力学模型,建立标准圆柱煤岩体试件的等效力学模型,推导含单一裂隙的纯煤岩试样等效轴向、径向与体积应变,并推广应用到含多种裂隙的多种介质组合结构,通过试验验证理论力学模型具有较好的可靠性。以淮南张集矿11-2煤层工作面回采为原型,通过数值计算得到3种典型开采的支承压力峰值集中系数,并推导出支承压力与水平应力分布表达式,其能综合考虑开采条件、影响范围与采动卸压产生的体积膨胀变形。建立体积应变与渗透率之间的多项式关系式,并给出采动条件下不同开采方式下的体积应变分布曲线与渗透率分布曲线,根据其各阶段的特征差异划分为不同的阶段,为工作面抽采瓦斯提供了理论依据。
Study on permeability distribution of coalface is of guiding significance in reasonable exploitation of gas. An equivalent mechanical model is established by simplifying the characteristics of pores and cracks. From the establishment of the equivalent mechanical model for a standard cylindrical coal-rock specimen, the equivalent formulas for axial, radial and volumetric strains are derived for coal-rock samples containing a single crack, and then are extended to the application in a variety of media combinations containing multiple cracks. The theoretical mechanical model shows good reliability by experimental verification. Based on the prototype of 11-2 coal seam mining face of Zhangji Mine in Huainan, the peak concentration factors of abutment pressure under three typical mining layouts are obtained by numerical calculation. An expression for the distribution of abutment pressure and horizontal stress is derived considering different mining layouts, different stages and volume expansion induced by mining. By establishing a polynomial relationship between volumetric strain and permeability, the distribution of volumetric strain and permeability under different mining layouts is obtained, and divided into different stages according to their various characteristics. It may provide a theoretical basis for the coal mine methane.