煤层瓦斯压力理论解析与影响因素分析

Theoretical analysis and influencing factors analysis of coal seam gas pressure

瓦斯压力和应力是煤与瓦斯突出发生的必要条件,揭示瓦斯压力与应力的关系对煤与瓦斯突出机理的研究有重要意义。在分析解放层开采对瓦斯压力影响规律和煤与瓦斯突出过程中瓦斯压力变化规律的基础上,根据气体状态方程和多孔介质有效应力理论,结合煤层孔隙度与应力的关系,得到了煤层瓦斯压力的解析解,分析了影响因素对瓦斯压力的影响规律。研究结果表明,应力是影响煤层瓦斯压力的主要因素;瓦斯压力受应力敏感系数α、地温梯度β、地应力梯度D等因素的影响,且与各因素存在正相关的非线性关系,在其他影响因素不变的情况下,煤层应力敏感系数α、地温梯度β、地应力梯度越大,瓦斯压力D越大;煤层应力敏感系数α越大,瓦斯压力对应力的变化越敏感;地应力梯度D和地温梯度β在煤层深部时对瓦斯压力的变化影响作用显著。

Gas pressure and stress are the necessary conditions for the occurrence of coal and gas outburst.Revealing the relationship between gas pressure and stress is of great significance to the mechanism research of coal and gas outburst.Based on the analysis of the impact of mining in the liberated layer on gas pressure and the variation of gas pressure during coal and gas outburst processes,according to the gas state equation and the effective stress theory of porous media,combined with the relationship between porosity and stress of coal seam,the analytical solution of coal seam gas pressure equation is obtained.The influence law of influencing factors on gas pressure is analyzed.The results show that stress is the main factor affecting the gas pressure of coal seam.The gas pressure is influenced by the stress sensitivity coefficientα,the geothermal gradientβ,the in-situ stress gradient D and other factors,and there is a positive correlation nonlinear relationship with each factor.Under the same other influencing factors,the greater the stress sensitivity coefficientα,geothermal gradientβ,and the in-situ stress gradient D of coal seams,the greater the gas pressure.The larger the stress sensitivity coefficientαof coal seams,the more sensitive the change of gas pressure to stress.The in-situ stress gradient D and geothermal gradientβhave a significant impact on the change of gas pressure in the deep coal seam.