Study on surrounding rock control technology of gob-side entry passing through fault fracture zone

Taking W3₂20 mining roadway of Qianyingzi Coal Mine as the engineering background, based on the distribution characteristics of internal and external stress field of gob-side coal mass and the limit equilibrium theory of narrow coal pillar for roadway protection, and combined with the specific geological conditions of the mine, the reasonable width of narrow coal pillar was determined; under the condition of adjacent working face mining and gob-side entry driving passing through fault fracture zone, FLAC^3D numerical simulation software was used to analyze the stress distribution and plastic failure response characteristics of surrounding rock at different section positions. The paper expounded the surrounding rock control difficulties and roadway support countermeasures of narrow coal pillar gob-side entry passing through fault fracture zone, and put forward the combined support technology of "advance grouting reinforcement + high strength and high pre-stressed bolt + roof reinforcement long cable + KTM4 steel belt + rhombus steel mesh". The results show that: based on theoretical calculation and field practice, the reasonable width of narrow coal pillar is 5.2 m to 7.1 m for gob-side entry of gently inclined medium thick coal seam passing through fault fracture zone; when simulated gob-side entry passes through the fault, the cross-section of the roadway changes and the stress is adjusted greatly. There is no stress concentration at the solid coal side and the coal pillar side. The stress of the coal pillar is very weak, the plastic damage range of the surrounding rock of the roadway is further expanded, and the roadway is subjected to severe extrusion deformation. The engineering practice shows that the convergence deformation of roadway tends to be stable 36 d after the support completion, and the maximum deformation of coal pillar side roof, solid coal side roof, coal pillar side and solid coal side is 66 mm, 62 mm, 59 mm and 47 mm respectively, the overall deformation of gob-side entry is small during the mining period and does not affect the normal mining of the working face, 6 m narrow coal pillar and strong combined support technology can ensure the stability of surrounding rock of gob-side entry passing through fault fracture zone.