下保护层开采上覆煤岩体卸压效果及保护范围研究

以晋城矿区为工程背景,开采9号煤层作为3号煤层保护层,开展下保护层开采试验。采用数值模拟手段,研究下保护层开采上覆煤岩体卸压效果及被保护层煤体膨胀变形规律,并确定有效保护范围。研究结果表明:保护层工作面开采后,上覆煤岩体出现分区卸压效应,距离工作面垂直距离越远,岩层卸压程度越不明显。被保护层倾向卸压角为63°,走向卸压角为60°。采空区中部被保护层膨胀变形率保持在4‰左右,为稳定卸压区域。现场工业试验后,通过钻孔电视发现被保护层煤体受采动影响产生了离层裂隙。煤层瓦斯参数测定表明:被保护层煤体瓦斯含量、瓦斯压力均有所降低,保护层开采起到了效果。

Research on pressure relief effect and protection range of overlying coal and rock mass in mining of lower protective seam

Taking Jincheng mining area as the engineering background,the 9#coal seam is mined as the 3#coal seam protective layer,and the mining test of the lower protective layer is carried out.By means of numerical simulation method,the pressure relief effect of overlying coal and rock mass and the expansion and deformation law of the protected coal seam are studied,and the effective protection range is determined.The research results show that after the mining of protective seam working face,the overlying coal and rock show the zonal pressure relief effect,that is,the farther the vertical distance from the working face is,the less obvious the degree of pressure relief is;the dip relief angle of the protected layer is 63°and the strike relief angle is 60°;the expansion deformation rate of the protected layer in the middle of the goaf is about 4‰,which is a stable pressure relief area.After the field industrial test,through the borehole television,it is found that the coal body in the protected layer has produced the separation fracture under the influence of mining.The determination of coal seam gas parameters shows that the gas content and gas pressure of the protected layer are reduced,and the protective seam mining has played an effect.