Application Research On Gas Outburst Prevention Technology In Coal Seam With Floor Drainage Roadway In 1307 Working Face Of Zhaozhuang Coal Mine

Since the beginning of the twenty-first century,China's economy has developed rapidly and industrialization has advanced rapidly,and many achievements have been made.More and more raw materials are consumed in industrial production,especially the demand for coal continues to grow rapidly,which requires coal enterprises to produce efficiently.Gas has always been a constraint on the rapid production of coal.Therefore,in order to avoid gas accidents,the management of gas must be strengthened in the process of extraction to ensure the safety of coal mining.At this stage,Zhaozhuang mine mined no.3 coal seam soft,poor breathability,high coal seam gas content,geological conditions are complex,resulting in coal seam gas pre-pumping there is a great difficulty.The main problems in the process of gas pre-pumping are the difficulty of construction,the low drilling rate,the difficulty of pre-pumping gas,and the concentration of extraction can not meet the design requirements.The method of pre-pumping gas for this coal seam drilling can not effectively solve the problems of small gas extraction,long pre-pumping time,rapid attenuation and blind spot extraction,resulting in the pre-pumping effect of coal gas is not ideal,affecting the normal excavation and re-mining of the mine,which leads to the mining tension of the mine and affects the safe production.Effective pumping of gas is the key to the safe production of Zhaozhuang Mine.Based on the field test and theoretical analysis,this paper studies the relationship among the diameter,angle,spacing and pre-drawing time of the holes,in order to guide the optimization of the bottom-drawing roadway level and the layout of the holes.The main findings are as follows:(1)The relationship between stress changes around drilling and initial stress,aperture and drilling angle of perforated drilling is studied.The increase of borehole diameter will lead to the increase of pressure relief range in the coal seam,which will cause the stress concentration area to shift to the deep coal seam,the stress in the stress concentration area around the borehole increases to a greater extent than that in the initial stress,but in the coal seam with high strength,the higher the initial stress,the greater the stress concentration in the horizontal direction of the Borehole,the larger the pressure relief range in the vertical direction,the higher the pressure relief degree.(2)The relationship between perforated drilling inclination,aperture,pumping negative pressure and extraction influence range was studied.Changes in drilling inclination affect the radius of the impact when drilling through a layer to extract gas.It is calculated that when the inclination is 75 degrees and 90 degrees,the radius value of the gas extraction effect of drilling is the smallest,when the diameter of the drilling is gradually increased,the radius of the extraction effect of drilling is gradually increased,but the increase is gradually smaller and eventually becomes zero,and the relationship between the extraction influence radius of drilling and the extraction of negative pressure and pre-pumping time has similar laws.(3)In this paper,by analyzing the spatial position relationship between the bottom pumping lane and the coal lane,the spatial position of the two is determined.In order to achieve the desired effect of gas treatment method in the bottom pumping lane area,the spatial relationship between coal lane and bottom pumping lane should be optimized.The above research results are of great theoretical and practical significance for optimizing the layout and parameters of boreholes and improving the effect of gas permeability enhancement in pre-drainage coal seams.