Research On Roadway Deformation Affected By Multiple Mining Under Coal Pillar For Ultra-Close Multi-Seam In Da Liuta

Due to the tension between mining and mining,some coal mines in the Da Liuta mine must consider the mining method of the upper and lower coal seam when the mining is very close.Sometimes the minimum distance between the upper and lower coal seams is only 0.8m,how to meet the premise of high yield and high efficiency production of the Da Liuta mine is very urgent for us to carry out the safe mining of the very close coal face.Considering that the lower seam roadway under the coal pillar is not only affected by the stress concentration,but also because the interval between the layers is very close,it may cause the roadway to be affected by 4 times of mining,and increase the risk of mine safety.Therefore,in order to solve the problem of safe and efficient mining of the same mining face in the shallow buried deep and near seam in the super large mine,it is necessary to study the deformation law of the roadway under the impact of multiple mining under the wide coal pillar in the Da Liuta coal mine,and find out the most reasonable arrangement scheme for the roadway under the influence of multiple mining.On the basis of this,the paper carried out the study on the deformation law of the roadway under the multiple mining pillar of the very close coal seam in the Da Liuta coal mine by means of field measurement,theoretical analysis and numerical simulation,and provided guidance for the mine safety production.Through the field measurement of the roof and floor of the 12315 working face and two sides of the roadway,the influence range of the mining face to the roadway is about 80 m,and the increase of the surrounding rock deformation is only 20~30mm.Through the theoretical calculation of the stress model of surrounding rock under the affected coal pillar under the influence of coal pillar,the change law of the surrounding rock of the roadway with different layout is obtained by the vertical stress,horizontal stress and shear stress under the influence of the upper coal seam,and the results of the theoretical calculation are verified by the FLAC3 D numerical simulation software.Theoretical calculation can preliminarily determine the selection of roadway layout plan for lower coal seam.Based on the geological conditions of the close range coal seam in the Da Liuta mine and the first use of the roadway support method,the results show that the deformation of the surrounding rock under the coal pillar increases with the increase of the outer fault distance under the buried depth of 100 m,and the deformation of the surrounding rock under the coal pillar increases with the interval of the interval of 2~6m.The original way of supporting and roadway layout is only applicable to the depth of 100 m depth.The roadway is damaged seriously when the depth of the buried depth is more than 200 m.Therefore,the supporting parameters of the roadway are optimized.By changing the spacing of the roof bolt,the spacing of the anchor cable and the width of the coal pillar of the coal seam section,the roadway under the buried depth can be solved when the depth of the buried depth exceeds 200 m.The width of coal pillar in the coal seam of the Da Liuta coal mine is optimized.When the depth of the coal seam is 100 m,the width of the coal pillar in the upper seam section can be set to 20 m,and the ultimate deformation of the top and floor of the roadway and the two gang is 357.45 mm and 305.42 mm after the influence of multiple mining action.