Study On Gas Migration Law And Drainage Technology In Goaf Of Large Mining Height Face In Xiahuo Coal Mine

The Xiahuo coal mine of Changzhi Sanyuan Zhongneng Coal Industry is a high gas outburst mine.As the mining depth increases,the coal and gas outburst becomes more severe.Aiming at the problem of high gas emission in the goaf of the large mining height working face,which threatens the safety of the working face,this paper has carried out the study on the division of the “three zones” of the goaf of the large mining height and the law of gas migration.It has important engineering practical significance to provide technical support for gas control in the goaf of a large mining height working face to ensure safe production in coal mines.In this paper,the 2301 working face of Huo Coal Mine is the research object,and the characteristics of gas occurrence,basic parameters of gas drainage,and gas drainage plan of this working face are studied.The laboratory and numerical simulation analyze the effect of mining cracks in the overlying strata during mining of the working face.The evolution law has determined the "three zones" parameters of the goaf;the flow field and gas concentration distribution characteristics of the goaf are studied;the drainage drilling construction technology and parameters are compared and optimized,and it is proposed to be suitable for 2301 Gas drainage technology in the goaf of the working face.Concluded as follow:(1)The gas occurrence and emission characteristics of 2301 working face of Xiahuo Coal Mine are analyzed,and it is found that gas emission is more serious in the goaf and adjacent coal seams of the stoping face.A suitable gas extraction plan was formulated,including two parts: the main part is the extraction of the gas in the mining layer,and the extraction of the gas in the goaf of the mining layer and adjacent coal seams as a supplement.(2)Analyze the movement characteristics of the overburden rock after mining,and arrange the pressure relief gas drainage boreholes in the "O" ring.Using empirical formula,UDEC numerical simulation software and laboratory similar material simulation three methods,comparative analysis of the evolution law of overburden mining cracks in 2301 working face mining,using on-site measurement methods to verify the calculation and simulation results,obtained Calculating the "three zones" height of the overburden goaf is the best method,that is,the UDEC numerical software simulation method is used to determine the "three zones" distribution range of the large mining height working face.The simulation result is 2301 work.The surface coal seam roof is below 12.65 m is the collapse zone,12.65～49.4m is the fracture zone,and above49.4m is the curved subsidence zone.(3)PHOENICS program software based on SIMPLE algorithm is used to establish a mathematical model of stope gas migration based on the theory of fluid mechanics.The simulation of the goaf of 2301 working face under both non-draining and gas drainage conditions,it is obtained that when the goaf is not extracted,the air leakage in the goaf is serious,and the coal pillars near the back of the goaf are The corners of the return air tend to accumulate gas.Under the condition of gas drainage in the goaf,the amount of gas emission from the working face is reduced,and the average gas emission concentration at the return air corner of the goaf is also greatly reduced.(4)In order to improve the effect of gas drainage in the goaf and adjacent coal seams,the original technology and technology will be further improved in terms of optimizing the drilling layout method,improving the quality of the hole,and optimizing the negative pressure drainage.According to the actual conditions of drainage in Xiahuo Coal Mine,the drainage drilling construction technology,sealing length and sealing depth are determined.This paper has 46 figures,14 tables and 87 references.