Analysis of the stability of the roadway surrounding rock affected by mining in the close undermined coal seam

Aiming at the problems of deformation and destabilization of the upper track roadway and poor stability of the roadway surrounding rock affected by mining in the close undermined coal seam. This paper takes the south flank track “Y”-type roadway about 12 m above the 14148 working face of in the north area of Zhangji Coal Mine as the engineering background, and analyzes the layer relationship between the roadway and the working face by using the empirical formula of “vertical three belts”. This paper adopts the method of numerical simulation combined with on-site practice to study the stress distribution characteristics and displacement evolution law of the overburden roadway in the process of mining back to the close undermined coal seam, and determines the key support parts of the roadway. The results show that the overburden roadway is under the influence of overburden fissure zone, the surrounding rock stress is affected by the concentration of over-support pressure in the working face, showing the trend of increasing and then decreasing sharply, the surrounding rock is asymmetric deformation, and the deformation rate with the advancement of the working face show a three-stage law, the deep part of the roof show a gradual increase and then a smooth trend, and the shallow part of the layer shows a trend of increasing and then decreasing. On this basis, the pre-mining anchor cable pre-reinforcement + post-mining U-shaped shed “reinforcement” roadway support technology is proposed. Numerical simulation comparison results show that after the reinforcement support, the stress of the two gangs of the roadway has increased by 9 MPa, the top plate subsidence has been reduced by 103 mm, and the displacement of the weak points of the roadway has been greatly reduced, and the effect of the reinforcement support control is remarkable. The measured results show that the support scheme can effectively control the deformation of roadway surrounding rock and ensure the safety of mine production.