Study On Depressurized Mining In Double Coal Mining Face Of Upper Protective Layer On Numerical Simulation And Gas Control Technology

The equal width of the protective layer and the coal mining face of the protected layer is an important technical means for achieving equal and continuous use of coal mining facilities in coal mine underground mining face.Based on the theory of protective layer mining,gas drainage and coal and gas outburst prevention,this paper combines the geological engineering overview of coal seam gas in the mining area 82 of QInan Coal Mine and uses the combination of theoretical analysis,numerical simulation and site inspection to study it.The pressure relief effect of the working face of the protective layer working faces 7₂25 and 7₂27 after the pressure relief mining of the Double coal mining face on the mining area was studied.The main results are as follows:（1）Based on the theory of mine pressure,using the elastic mechanics knowledge to build a protective layer on the double face mining inclined direction slab vertical additional load mechanical model,reveals that the protective layer on the double face mining from the mechanics underlying the stress distribution law of coal and rock is studied on the protective layer of double face after the lower pressure relief features of protected coal seam mining.The results show that the"scoop shape"continuous stress increment reduction zone is formed in the underlying coal rock mass under the goaf floor in the direction of the mining tendency of the upper protective layer,and the larger stress increment zone is located inside the outer coal wall of the double coal mining face.（2）Based on the finite element theory,using the FLAC^3D numerical simulation software,a three-dimensional model of the upper protective layer double coal mining face mining was established.The temporal and spatial evolution of the vertical stress field and the vertical displacement field of the 72-coal under the mining of the protective layers 6₁23 and 6₁25 in the QInan Coal Mine are discussed.The deformation deformation of the 72 coal in the protected layer is also investigated.The tendency of the pressure relief after the numerical simulation experiment and the direction of the pressure relief in the strike direction;based on the geological conditions of the coal seam and gas in the mining area 82,the direction and inclination of the working face7₂25 were implemented in the floor transport corridor of the working face 6₁25respectively.The research and investigation of the borehole obtained the pressure relief protection range of the coal mining face 7₂27 of the protected coal seam after the working face 6₁25 of the upper protective layer 6 coal seam was recovered.The numerical simulation experiment value was observed in co MParison with the measured results and numerical simulation.It is close to the field test and verification values,and both are within the measured pressure relief range.（3）Based on the above theoretical analysis and field investigation results,the model of gas control in 82 mining area of Qinan coal mine is studied.After the implementation of"ventilation measures+goaf semi-closed buried pipe+high roadway drilling+bottom plate intensive drilling through the layer"gas management program,through analyzing the change trend of gas extraction amount and concentration and the advancing process of working face,we can find that the gas control scheme of application effect is good and the unloading process elimination effect is obvious,which provides a guarantee for the safety and efficient production of coal mine.The results of this paper can be used for reference and guidance in similar mining areas and other coal seam gas occurrence conditions.