Research On The Control Technology Of Coal Pillar Concentration In The Proximal Lower Strata Of Shangwan Coal Mine

Because Due to the small distance between the coal seams of the close coal seam group,the mining of upper coal seams is bound to have an impact on the mining of lower coal seams.Upper coal seam 12 upper coal face of Shangwan Coal Mine adopts two-wing mining method,and lower seam 12#coal adopts single-wing mining method.Due to the change of coal mining technology,it is affected by the protection coal pillars of concentrated roadway left over from double-wing mining of upper coal seam.Problems such as uneven roof rock load in the lower coal seam and frequent occurrence of abnormal mine pressure.Therefore,this paper uses theoretical analysis methods,numerical simulation methods,and on-site measured data to study the underground pressure phenomenon in the process of passing the overlying coal pillars at the 12301 working face of Shangwan Coal Mine.Analyze dynamic load mine pressure prevention and control technology,and formulate corresponding treatment measures.The main research results are as follows:According to the test of mechanical parameters of coal and rock mass,the mechanical properties of coal roof and floor and coal are analyzed,and the surrounding rock is classified;12#coal and 12#coal are soft coal,the distance between 12#coal and 12#coal is 17.9m,and the seam distance It is smaller and the overlying rock layer has higher strength.The direct roof is 3.78m siltstone,which belongs to the second type of moderately stable roof;calculated by the upper seam mining to the floor damage depth,the 12 upper coal seam mining has a floor damage depth of 12.7m,The destruction depth is less than the seam spacing(17.9m),indicating that during the normal mining process,the upper coal seam will not damage the coal structure of the lower coal seam;the stress disturbance range of the coal pillar is calculated,and the stress disturbance zone of the concentrated coal pillar to the lower coal seam is 60m,That is,the working face within 15m before and after the concentrated coal pillar is greatly affected by the coal pillar;according to the field pressure observation data,it can be known that the working resistance and the incoming pressure strength of the support are less than the rated working resistance of the support during normal mining.During the coal pillar,the working resistance and the pressure strength of the support will exceed the rated working resistance of the support;the numerical simulation shows that the mining of 12shangmei and 12#coal leads to the redistribution of the surrounding rock stress,which is ahead of the coal pillar,the coal pillar and the coal pillar The average values of abutment pressure are 9.3MPa,18MPa and 17.9MPa,respectively.When mining to the right edge of the coal pillar 5m,a peak of 21.3MPa appears in the goaf in front of the coal pillar.Take mine pressure prevention and control measures.The prevention and control measures for coal pillars at the working face are formulated,which are mainly divided into reinforcement support,face adjustment,and blasting pressure relief.Reinforcement measures such as erecting metal shed legs at intervals of 1m on the coal walls on both sides of the roadway;start 25m ahead of the working face,with the head of the machine 10m ahead of the tail of the machine;start deep hole blasting in front of the coal pillar 15m.The blasting pressure relief measures adopted by the company reduce the impact of concentrated coal pillars on the mining of the lower coal seam,reduce the appearance of mine pressure at the working face,and achieve safe passage through the area affected by the concentrated coal pillars;the results of on-site industrial tests show that"optimized pressure avoidance design"?The prevention ideas of"pre-mining prevention"?"mining time tracking prevention”and prevention measures effectively curb the impact of dynamic load on the roof during the process of passing coal pillars,so that the working face can safely and smoothly pass through the upper coal seam concentrated coal pillars.In summary,the research results not only solve the problem of over-concentrated coal pillars in Shangwan Coal Mine,and ensure the safe mining of coal mines,but also provide a scientific basis for the prevention and control of dynamic-loaded mine pressure in similar close-range coal seams.