特厚煤层综放开采坚硬顶板破断对瓦斯涌出影响

针对具有坚硬顶板的特厚煤层综放工作面周期来压期间瓦斯异常涌出问题,基于坚硬顶板"O-X"破断机理,从能量的角度分析了坚硬顶板破断回转对采空区的冲击过程,得到破断块体轴向作用力与采空区垮落煤岩碎胀系数之间的关系。同时研究了顶煤放出率及垮落煤岩碎胀系数对坚硬顶板破断回转前后采空区体积变化的影响规律,建立了周期来压期间采空区瓦斯涌出增加量计算模型,并与现场实测进行对比。结果表明:特厚煤层综放工作面坚硬顶板破断回转压缩了采空区体积,使采空区高浓度瓦斯涌向工作面,导致周期来压期间瓦斯异常涌出现象。塔山煤矿8214工作面周期来压期间采空区瓦斯涌出增加量理论计算值为14.5 m~3/min,与现场实测增加量相比误差在1.79%～8.83%,两者结果较为相符,验证了模型的正确性。

Effect of hard roof breaking on gas emission in fully mechanized sublevel caving mining of extremely thick coal seam

In terms of the issue of the abnormal gas emission during periodic weighting in the fully-mechanized sublev- el caving mining of extremely thick coal seam,based on the “O-X” type breaking of hard roof,the impact process of hard roof breaking to the goaf is analyzed from the view of energy to get the relationship between the axial force of bro- ken block and the broken expand coefficient of caving coal-rock in goaf. Besides,combined with the effect of the top- coal recovery rate and the broken expand coefficient of caving coal-rock on the volume change of goaf during hard roof breaking,the formula for gas emission increase in goaf during periodic weighting is established,and its results are com- pared with the measured data. The result shows that the volume of goaf is reduced by the breaking of hard roof in the fully-mechanized sublevel caving mining of extremely thick coal seam,so the high concentration of gas in goaf will be poured into the working face which leads to abnormal gas emission during periodic weighti3ng. The theoretical calcula- tion of gas emission increase in goaf for the 8214 working face of Tashan Mine is 14. 5 m³ / min,and the error is be- tween 1. 79% -8. 83% compared with the measured data. The results are consistent,which verifies the correctness of the formula.