Study On The Technology Of Gas Prevention And Control During Cutting Through Extra-thick Coal Seam For Shaft In Hujiahe Coal Mine

Coal and gas outburst is one of the most serious natural disasters in coal mine,,especially when the shaft is exposed to coal.The Hujiahe coal mine belongs to the high gas and rock burst mine,and the main mining no.4 coal seam is the deep extra thick coal seam.The mine plans to carry out the construction of no.2 air shaft,and will face the problem of coal mine shaft coal gas prevention.Therefore,it is of great practical significance and theoretical value to summarize the gas control experience during the construction of the main shaft,the auxiliary shaft and the return shaft of Hujiahe coal mine.Based on the analysis of geological conditions of Hujiahe mine,this paper sums up the factors that are not conducive to the vertical shaft uncovering.In field and laboratory determination of the main shaft,during and wind shaft uncovering coal area of no.4 coal gas pressure,gas content,gas radiation initial velocity,the gas adsorption constant,the gas basic parameters such as porosity,coefficient of robustness.Using single index method and comprehensive index method to predict coal outburst risk in wellbore,the prediction result indicates that the possibility of outburst risk in no.4 wellbore area is less.But considering the mine belongs to the gas of the mine and coal seam is buried deep thick coal seam,and the gas radiation initial velocity is large,to prevent the shaft uncovering coal in the process of large amounts of gas outburst danger,using the drill hole as the main gas prevention and control measures,Through the test of gas emission effect,the ?h2 value of the wet coal sample decreased from 21 OPa to less than 140Pa.The gas concentration before and after the gas emission from Ti was reduced from a maximum of 1.7%to 1.2%.The outburst risk was completely eliminated through gas emission.In the end,the coal seam is exposed by the vibration blasting method.Developed the determination of basic parameters,wellbore gas outburst danger prediction,prevention and control of gas,the gas emission effect test,blasting,vibration uncovering coal "five one" is suitable for deep mine specially thick coal seam wellbore uncovering coal outburst prevention technology,provides the shaft uncovering coal of similar conditions.