Research On Reasonable Layout And Classification Control Technology Of Mining Roadways In Underlying Coal Seams Of Xutuan Coal Mine

Under the downward mining mode of medium depth and close distance coal seams,there is a common problem of controlling the surrounding rock of the large cross-section and small coal pillars along the goaf in the underlying coal seam due to the significant fluctuations in coal seam spacing.This thesis takes the close range coal seam mining conditions of Xutuan Coal Mine as the engineering background,analyzes the failure characteristics of the mining floor of the overlying coal seam working face,determines the reasonable layout of the underground coal seam mining roadway based on the stress distribution law of the left coal pillar floor,and combines the roof stability characteristics of the underground coal seam mining roadway with different interlayer spacing conditions to carry out the roof classification research of the underground coal seam mining roadway,At the same time,based on the concept of strengthening support with thick anchor layers on the roadway roof,a classification control technology for the underground coal seam mining roadway roof in Xutuan Coal Mine has been proposed.The comprehensive application of theoretical analysis and numerical simulation combined research methods has revealed the characteristics of damage and failure of the mining floor of the overlying 7₁coal seam working face in Xutuan Coal Mine.The study shows that under different coal seam spacing conditions,the damage depth reaches about 5.5m,and the underlying 7₂coal seam is basically within the damage and failure range.Through comparative analysis,it has been determined that the 7₂coal seam mining roadway,namely the 7₂210 air roadway,is more reasonable to adopt the same inward staggered layout with a horizontal offset of 30m and a reserved width of 5m between the remaining coal pillars of the 7₁coal seam.A numerical simulation analysis model for the excavation and mining process of close distance coal seam groups with different coal seam spacing conditions under the same inward staggered arrangement was established,revealing the stress evolution law and stability characteristics of the surrounding rock of the 7₂210 air roadway roof under different coal seam spacing conditions.The results show that the overall deformation of the 7₂210 air roadway is small and the roof has stable bearing characteristics when the coal seam spacing is greater than 7.50m.Subsequently,combining theoretical analysis,numerical simulation,and on-site drilling observation results,the stability classification of the roof of the goaf roadway in the underlying coal seam was carried out,with a coal seam spacing of L,as follows:Condition Ⅰ:L<5.50m,poor roof integrity,fragmentation,and no empty roof self stabilization time;Condition Ⅱ:5.50m≤L<7.50m,with good roof integrity and a certain amount of empty roof self stabilization time;Condition Ⅲ:7.50m≤L,roof integrity and good self stability.Based on the strengthening support of the thick anchoring layer on the roof of the roadway and the prestressed full length anchoring technology,a specific classification control technology scheme for the 7₂210 air roadway has been developed and industrial experiments have been carried out.Engineering experiments have shown that the staggered layout in the same direction and the classification support scheme in the double goaf area of the roadway have significant application effects,improving the strength of the surrounding rock,fully utilizing the self-supporting ability of the surrounding rock,effectively controlling the deformation of the roadway,and the roadway section can fully meet the requirements of safe and efficient mining in the working face.There are 76 figures,6 tables and 80 references in this thesis.