| China has abundant proven coal resources,and its production and consumption of coal are among the first in the world.With the increase of coal mining depth,the previous gas drainage effect is not ideal,which seriously restricts the safe mining of coal mines.This paper takes the coal mining face of a high-gas mine in Heshun,Shanxi as the research goal.From the aspects of theoretical derivation analysis,physical similarity simulation test,and on-site industrial test analysis,etc.,it studies the evolution law of pressure relief gas migration channel under multi-factor conditions and applying the research results to the site,the following research results were initially obtained:(1)Through self-developed and improved fully-automatic variable dip angle two-dimensional physical simulation test platform,three test levels(height mining,dip angle,and propulsion speed)are selected as experimental variables to develop the evolution law of gas migration channel under different influencing factors Two-dimensional physical simulation experiment.It is found that with the increase of mining height,the height of the three belts has shown an increasing trend,and the proportion of fracture zones has increased from 48%to 60%.The height of the three belts increases with the increase of the coal seam inclination and decreases with the acceleration of the advancement speed.(2)Through the comparative analysis of the experimental results,it is found that the delamination amount changes in a "hump-like" shape in three stages and the delamination amount is selected as the judgment condition of the boundary of the gas migration channel.The spatial distribution characteristics,floor stress,penetration and subsidence of the pressure-relief gas migration channel were quantitatively analyzed,and the change rules of its related parameters were determined.The theory mathematical model of gas migration channel under the influence of multiple factors was constructed.(3)By calculating the fractal dimension of the gas migration channel under different conditions,the fractal characteristics of the development of the fracture network of the gas migration channel under different influencing factors are analyzed,and the development integrity of the gas migration channel is discussed.The results show that When the mining height is 6m,the fractal dimension of the gas migration channel is 1.07 times when it is 4m,and 1.23 times when it is 2m,showing a rising dimension.The fractal dimension shows a downward trend with the acceleration of the advancing speed.And the greater the coal seam dip angle,the fractal dimension of the gas migration channel is 1.68<1.69<1.71,showing an increasing trend.(4)Based on the actual mining conditions of the 302 face and combined with the analysis of the gas migration channel test simulation results,the layout of the three-dimensional gas extraction system is implemented for the face,and the microseismic monitoring during the mining period further monitors the layout parameters of the extraction method Through optimization,by monitoring the gas concentration changes in the working face and analyzing the treatment effect of the three-dimensional gas drainage in the working face,the rationality of the three-dimensional gas drainage system for the accurate gas drainage of high-gas working face pressure relief gas was verified.It has effectively solved the problem of gas overrun at the upper corner,etc.,and has ensured the safe mining of the working face to the greatest extent,thus also providing a powerful guarantee for the safe and orderly production of the mine.Reveal the evolution law of pressure relief gas migration channel under multi-factor conditions,establish a mathematical control model of gas migration channel and reservoir area affected by comprehensive factor conditions(mining height,advancing speed,coal seam dip angle),optimize gas drainage The layout parameters of the system provide a certain theoretical basis for the further development of precise gas drainage,and are of great significance for the improvement of the theoretical system of coal and gas mining. |
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