Study On Gas Transport Law And Coal Spontaneous Combustion Prevention And Control Technology Of Large Dip Angle Thick Coal Seam Mining In Baicheng Mining Area

This thesis takes Xinjiang large inclination thick coal seam mining area as the research object,and establishes numerical simulation of Xinjiang large inclination thick coal seam stratification mining through UDEC software,analyzes the top plate fracture development law in the process of thick coal seam stratification mining,and reveals the transport mechanism of gas and oxygen;establishes numerical simulation of gas dilution under different working conditions through COMSOL,studies the spontaneous combustion tendency level of coal samples with different water content,and determines the reasonable water retention amount to suppress the spontaneous combustion of coal samples in large inclination thick coal seam mining.The reasonable water retention amount for suppressing the spontaneous combustion of coal samples was determined,which provides prevention and control measures for gas gushing and coal spontaneous combustion in the stratified mining of thick coal seam with large inclination.The main research conclusions and results of this thesis are as follows.(1)Through UDEC numerical simulation,the numerical model of large-inclined thick coal seam stratification mining in Xinjiang mine was established,and the law of inter-seam fissure development during stratification mining was analyzed.It was proposed that the disturbance of large-inclined thick coal seam stratification mining would lead to the penetration of inter-seam fissures,resulting in the downward migration of toxic and harmful gas in the old void area of the upper stratification,revealing the law of fissure development and gas transport mechanism of stratification mining.(2)Through numerical simulation tests on the effect of nitrogen injection on gas replacement under different working conditions,it is found that nitrogen injection in the lower stratum can significantly reduce gas concentration and oxygen concentration,and a numerical model of nitrogen injection followed by extraction is constructed to analyze the dilution and replacement effect of the combined injection-pumping method on gas in the old void area,revealing the mechanism of the combined injectionpumping method to reduce the natural risk of coal in the void area by reducing oxygen concentration.(3)Through experimental research and field measurements,the effect of high water content of coal samples on coal spontaneous combustion is analyzed,and the conclusion that coal naturalization is promoted at low water content and suppressed at high water content is proposed.The optimal amount of water retention for spontaneous combustion was determined.There are 50 figures,14 tables and 104 references in this thesis.