Analysis Of Gas Outburst Risk In Thin Coal Seams Of Qinglong Mine In Guizhou

Gas outburst seriously harms coal mine safety production in China.With the increase of coal consumption and the decrease of coal reserves,thin coal seam has become a new mining target.In order to reduce the occurrence of gas accidents,it is particularly important to analyze the risk of gas outburst.Based on the systematic analysis of the geological characteristics of Qinglong Mine in Guizhou,this paper analyzes the failure types of coal and the structural characteristics of pores and fissures through macroscope observation and mercury injection test.Analysis of coal rock structure types and quantitative characterization by logging curves in borehole data.A gas data prediction model based on the main coal seam is established.The gas content and pressure in thin coal seam are reasonably predicted and their distribution characteristics are analyzed.It reflects the danger of gas outburst in thin seam of study area.The correlation coefficient between gas content,gas pressure,coal seam floor depth,coal seam thickness,coal rock structure and structural curvature was selected as the evaluation factor set,and the risk of gas outburst was evaluated by fuzzy clustering analysis.This study has obtained the following research results:(1)The sequence stratigraphy and sedimentary environment of Longtan Formation in the coal-bearing strata of the study area have good consistency in the coal accumulation period,and the later tectonic evolution has synchronization,which provides sufficient geological theoretical basis for predicting and evaluating the risk of gas outburst in thin coal seams by gas geological data of main coal seams.(2)The failure types of coal rock structure in the main coal seam in the study area are mainly"II,III,IV".The coal structure index of thin coal seam with 16 layers ranged from 1.65 to 2.24.The main failure types of coal rock in thin coal seam are"III,IV".(3)The elevation of coal seam floor decreases from NE to SW,and the structural forms of each coal seam floor are basically the same.The floor structural curvature of16 coal seam is not significantly different from that of representative thin coal seam,and the structural complexity of each coal seam is at the same level.The thin coal seam has the similar gas geological conditions as the main coal seam.(4)The gas content and gas pressure of the main coal seam in the study area are correlated with the buried depth of the coal seam floor,the thickness of the coal seam,the coal structure index and the structural curvature.The prediction model is constructed to predict the gas content and gas pressure of all 16 thin coal seams.The prediction results show that the gas content of the thin coal seam in the study area is more than 10 cm~3/g,and the gas pressure is greater than 1.0MPa.High pressure gas is a necessary condition for outburst.(5)The evaluation factor set combined with fuzzy clustering analysis was constructed,and the thin coal seam was divided into two categories according to the risk of gas outburst:one was 02 coal seam,04 coal seam,05 coal seam,09 coal seam,15coal seam,16 lower coal seam,19 coal seam,20 coal seam,21 coal seam,22 coal seam,23 coal seam,23 lower coal seam,25 coal seam,27 coal seam,30 coal seam,which was similar to 16 coal seam and 18 coal seam,had high outburst risk.The other type is coal seam 03,with medium outburst risk.