复采工作面瓦斯涌出随地表气压变化的相关性分析及对策

Correlation Analysis and Countermeasure of Gas Emission with Atmospheric Pressure in Re-mining Face

以西安矿为例,发现残复采工作面地表气压的突然下降造成井下回风流瓦斯涌出异常增大,且瓦斯异常涌出通常滞后于气压下降3~6 h左右。异常涌出的瓦斯浓度曲线分"极峰"、"波动""波动+极峰"3种类型。分析了地表气压影响井下复采工作面回风流瓦斯浓度的基本原理,认为巷道空气压力的绝对值影响煤孔隙壁上瓦斯的"解吸葑吸附"速度,巷道空气压力的相对变化引起的压力梯度影响煤孔隙和裂隙中瓦斯运移速度。结合实测数据,得出了初始地表气压条件下,残煤复采工作面回风瓦斯浓度随地表气压变化的量化方程。最后根据大气压降对复采面瓦斯涌出的影响原理,提出切断瓦斯向外涌出的通道和抵消大气压降这2种防治思路。

Taking Xi’an Mine as an example,it is found that the sudden drop of the atmospheric pressure causes the abnormal increase of gas emission in underground return airflow,and the abnormal gas emission usually lags behind the pressure drop of about 3-6 h.The abnormal gas emission curve is divided into three types:"polar peak","fluctuation"and"fluctuation+polar peak".The basic principle of the atmospheric pressure affecting the gas concentration of return air flow in the underground mining face is analyzed.It is considered that the absolute value of the air pressure of the roadway affects the"desorption and adsorption"speed of the coal pore wall gas.The pressure gradient caused by the relative change of the air pressure of the roadway affects the gas migration velocity in the pore and fracture.Combined with the measured data,the quantitative equation of the change of the return gas concentration with the atmospheric pressure in the residual coal recovery face under the initial surface pressure is obtained.Finally,according to the influence of the atmospheric pressure drop on the gas emission,two kinds of prevention and control ideas are proposed to cut off the gas migration channel or to offset the atmospheric pressure drop.