瓦斯抽采钻孔对底抽巷围岩破坏效应分析

Analysis of Damage Effect of Gas Drainage Borehole on Surrounding Rock of Bottom Drainage Roadway

为解决某煤矿抽采钻孔破坏引起5308底抽1巷失稳的问题,利用理想弹塑性力学模型分析了引起穿层瓦斯抽采钻孔破坏的主要因素,指出内聚力、内摩擦角和弹性模量是造成钻孔围岩破坏的主要因素;利用数值模拟分析了不同孔径和不同应力扰动时瓦斯抽采钻孔的破坏范围:掘进扰动时,钻孔破环范围为直径1.5倍,二次回采扰动时钻孔破环范围为直径2.5~3倍。据此提出将5308底抽1巷布置在K_(6)灰岩以下泥岩和砂质泥岩中,并调整支护参数,对巷表进行喷浆封闭的技术方案。结果表明:底抽巷层位和支护参数调整后,顶底板移近量由之前的790 mm缩短为105 mm,两帮移近量由1264 mm缩短至221 mm,保证了矿井的安全生产。

In order to solve the problem of instability of 5308 bottom drainage No.1 roadway caused by drilling failure in the coal mine,the main factors causing borehole failure in gas drainage through layer are analyzed by using ideal elastic-plastic mechanical model.It is pointed out that cohesion,internal friction angle and elastic modulus are the main factors leading to the failure of borehole surrounding rock.The failure range of gas drainage boreholes with different pore sizes and different stress disturbances is analyzed by numerical simulation:the failure range of gas drainage boreholes is 1.5 times of diameter in drivage disturbance and 2.5 to 3 times of diameter in secondary mining disturbance.On the basis of this,a technical scheme is put forward that 5308 bottom pumping No.1 roadway is arranged in mudstone and sandy mudstone under K_(6) limestone,and the support parameters are adjusted to seal the roadway surface by shotcreting.The results show that after the adjustment of the strata and support parameters of the bottom pumping roadway,the moving amount of the roof and floor is reduced from 790 mm to 105 mm,and that of the two sides is reduced from 1264 mm to 221 mm,which ensures the safety of mine production.