Research on feasibility of double -roadway layout below coal pillar in shallow and close coal seam

For the feasibility of double -roadway layout in hypogynous coal seam in A Coal Mine of Shendong mining area when working faces in shallow and close coal seam are synchronously mined, roadway deformation and plastic zone failure characteristics below an overburden 35 m wide coal pillar are researched by use of numerical simulation, physical model and field measurement. The results indicate that the greater the cover depth is, the larger the roadway deformation is. Especially, cumulative displacement between roof and floor reaches 2.5 m with serious roadway deformation when cover depth is 300 m, and plastic zones of coal pillar between the double roadways in hypogynous coal seam completely link up, which shows unstability of the coal pillar. Considering the actual cover depth is only about 100 m in No.3 panel of the mine, the simulated cumulative displacement between roof and floor of roadway below the coal pillar after multi -mining is 180 mm and the actually measured one is 32 mm, the simulated cumulative displacement between two sides is 118 mm and actually measured one is 24 mm, and plastic zone failure scope of roadway surrounding rock is only 0.5 m, which is stable on the whole. The research verifies that double -roadway layout below coal pillar in No.3 panel is feasible in some cover depths to satisfy requirements of safe and efficient production in working face.