倾斜特厚煤层采空区孔隙率分布规律研究

Research on porosity distribution laws of goaf in inclined extra-thick coal seam

为了研究倾斜特厚煤层综放开采采空区孔隙率分布规律,确定采空区高位钻孔位置,有效治理采空区瓦斯灾害,以硫磺沟煤矿9-15(06)工作面为例,采用UDEC数值模拟软件研究采空区覆岩垮落和裂隙演化规律,根据采空区覆岩下沉量,计算得到采空区孔隙率三维分布规律。研究结果表明:倾斜特厚煤层采空区覆岩位移云图在垂直方向呈3段分布,以距离工作面底板23 m和80 m为分界线,位移矢量密度显著降低,冒落带高度为23 m,与经验公式25 m基本一致,大于薄、中厚和厚煤层;受倾角影响,垮落矸石滑移、充填采空区下端,覆岩下沉量呈非对称椭圆形,中上部下沉量最大;冒落带孔隙率在上、下隅角处最大,中上部最小,随着覆岩高度增加,采空区边缘处和深部孔隙率差值逐渐减小。研究结果为倾斜特厚煤层采空区瓦斯抽采高位钻孔的布置提供了理论基础。

In order to study the distribution laws of porosity in the goaf of fully mechanized top coal caving in the inclined extra-thick coal seam,determine the location of high-level borehole in goaf,and effectively control the gas disasters in goaf,taking the 9-15(06)working face of the Liuhuanggou coal mine as an example,the UDEC numerical simulation software was used to study the evolution laws of overburden strata collapse and fissures in the goaf,and the three-dimensional distribution laws of porosity in the goaf were obtained according to the subsidence amount of overburden strata in goaf.The results showed that the cloud map of overburden strata displacement in the goaf of inclined extra-thick coal seam presented the three-section distribution in the vertical direction,with 23 m and 80 m above the floor of working face as the dividing lines.The displacement vector density decreased significantly,and the height of caving zone was 23 m,which was basically consistent with the empirical formula of 25 m and larger than thin,medium-thick and thick coal seams.Affected by the dip angle,the collapsed gangue slipped and filled the lower goaf,and the subsidence amount of overburden strata presented the asymmetrical ellipse shape,and the subsidence amount of the middle and upper part was the largest.The maximum porosity of the caving zone located at the upper and bottom corner,and the minimum porosity located at the middle and upper part.As the height of overburden strata increased,the difference in porosity between the edge and the deep part of goaf gradually decreased.The results provide theoretical basis for the layout of high-level boreholes for gas drainage in the goaf of inclined and extra-thick coal seams.