| During the process of producing of low-gas thick seam mine,abnormal gas emission is one of the reasons that affect the safe and efficient production of mines.Gas abnormal emission will cause gas overrun at upper corner of working face,which is a serious threat to the lives of underground staff.How to effectively solve the gas overhang in the corner of the low-gas thick seam and ensure the safe and efficient production of the working face is an urgent problem to be solved.It is of great significance to study the characteristics of abnormal gas emission,formulate reasonable solutions,and solve the gas overrun at the upper corner,which is of great significance to ensure the safety of mine production.The thesis takes 402 Xiaoyu coal mine which has the characteristics of low-gas thick coal seam as an example.The characteristics of gas abnormal emission and comprehensive treatment technology in Xiaoyu coal mine are studied by comprehensively using field test,laboratory test,theoretical analysis,computer numerical and field experiment.Coal,stratum and geological structure in Xiaoyu coal mine is understood through field investigation.The gas content,gas pressure and attenuation coefficient of No.5 coal seam were tested on site.The 5#coal adsorption constants and other basic gas parameters were tested in the laboratory.The gas emission of 8204 working face and the gas concentration in the upper corner during the mining process were observed by field test.The law of gas emission from fully mechanized top coal caving face was analyzed and the area where gas was abnormally discharged was delineated.The influence of geological factors and mining factors on gas emission is expounded.The cause of abnormal gas emission was found.By using the improved sub-source prediction method,the gas emission from working face and goaf was predicted,and the source of gas emission from goaf was obtained.The measured gas emission from the working face confirms the correctness of the improved sub-source prediction method and confirms that the goaf is the main source of gas emission from the working face.The scheme of pre drainage gas in this seam is put forward.That is the high-level bedding drilling+gob buried pipe extraction program and the top pumping tunnel gas drainage three kinds of gas treatment program.Comparing the gas treatment effect and economic cost of the upper-corner gas of the three schemes,the gas control program of top-pumping roadway is selected.In this paper,the Fluent module in ANSYS is used to simulate the extraction of roof drainage roadway in different layers.The influence of the horizontal offset and the vertical height of the top-draw aisle on the gas concentration in the upper corner were analyzed,and the optimal arrangement of the top-drawover lane was determined.Aiming at the problem of gas overrun in the upper corner of 402 plates,a field experiment was carried out on the 8206 working face by using the top entry roadway,and the effect test was carried out.The gas concentration in the top suction roadway,the return air lane and the upper corner is within the scope of safe production,and the roof suction roadway effectively solves the problem of gas overrun in the upper corner.The research results of the paper confirm the characteristics of abnormal gas emission at the upper corner of Xiaoyu coal mine and find out the reason of abnormal gas emission.Based on the improved sub-source prediction method and the amount of gas emission from the goaf,the measures of gas drainage by top-draw pumping are proposed.The research results have good reference significance for the treatment of gas abnormal emission in low gas thick coal seam. |
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