Research On Strata Behavior Regularity Of Shallow Coal Seam Under Goaf Of Room And Pillar In Huoluo Bay Coal Mine

The 2-2 coal seam in the Huoluo Bay coal mine has been mined and the mine is going to be mined in the lower part of the 3-1 coal seam.Due to the increasing of coal production capacity,comprehensive mechanized coal mining with longwall method on the 3-1 coal seam.2-2coal seam depth is shallow,mining on the surface of a greater impact.Hence,the use of the pillar coal mining process recovery,which resulted in 3-1 coal seam mining will have aninfluence on the 2"2 coal pillar mined learies.grasp the shallow coal seam near the mined-out mining under the mining pressure behavior,to ensure that the 3-1 coal seam efficient and safe mining,which has become the Huoluo Bay coal mine need to solve the urgent problem.The statistical analysis of the form of coal pillar in the coal seam of 2-2 coal seam is analyzed.The remaining pillar can be divided into apillar,and the pillar is separated from each other of threecategories.The key layer theory is used to determine the two key layers in the overlying strata of the 3-1 coal seam.The initial pressure of the main critical layer is 84.96 m and 33.28 m,respectively,and the sub-critical layer is the pressure of the column is 72.04 m and 19.33 m respectively.The stress distribution model of coal pillar is established,and the stress distribution of coal pillar is analyzed.2-2 coal pillar The stress of coal seam mining is less affected,and it has a certain pressure relief effect.The 20 m pillar and 50 m pillar can produce stress concentration in the lower rock formation.Based on the numerical simulation method,the numerical model of the mining under the pillar goaf is established,and the distribution of the stress in the coal seam is analyzed.The effect of the advanced bearing pressure is 40 m-50 m,the peak value of the bearing pressure is 16.9 MPa and the stress concentration coefficient is 3.01.When the mining is carried out in 20 m and 50 m pillars,the stress of the coal body is high,reaching 22.5 MPa,the maximum value of the stress concentration is 5.00,The effect of the advance bearing pressure is 65 m?70 m,which can cause the impact damage.While using the similar material simulation method,the stress change of the residual coal pillars after mining and its influence on the bottom plate are analyzed.The initial pressure step of the coal seam is 34?36 m,the time step is below the 8 m pillars 10?27 mi.the 20 m and 50 m pillars below the cycle to press the step distance of 8 to 16 m.The coal seam pressure behavior is the result of the interaction between the sub-critical layer and the coal pillar of the 2-2pillar mined-out area.The results of the study have some guiding significance for preventing and controlling the occurrence of strata behavior in mine mining under similar conditions.