Analysis and prevention measures of tunnel damage in close distance coal seam “upper mining and lower excavation”

The “upper mining and lower excavation” roadway is mainly affected by multiple dynamic pressures, resulting in strong underground pressure behavior and difficult support. The upper coal seam extraction makes it difficult to drive the lower roadway, and the deformation of the surrounding rock intensifies. This article takes the 3201 return air roadway as the engineering research background, and uses FLAC^3D software to analyze the vertical stress distribution characteristics of coal pillars with different widths, the impact of lower roadway layout on its stability, the stress distribution of opposite “upward mining and downward mining”, and the spatiotemporal relationship, providing design basis for roadway layout and excavation. This research method can provide reference for mines under similar conditions. Practice has shown that during the upper and lower mining periods, if the roadway adopts an internal staggered layout, after entering the disturbance period, the upper mining should be stopped and staggered construction be carried out, and reinforcement support is adopted for the lower roadway, the deformation of the surrounding rock of the roadway can be effectively controlled.