Study on stability of underlying room and pillar old goaf in close coal seam and mining of the upper coal seam

Possible issues during mining of the upper coal seam in old goaf nearby seams, including step subsidence, gas overflow goaf, and roadway around rock fragmentation. Using Hanjiawa Coal Mine’s mining, which takes place 28 m above working face lower seam, as research’s focal point. The paper focuses on self-stability pillar failure form floor, roof caving rule bearing capacity interlayer strata using stability evaluation system, field geological borehole electrical logging peeping, finite element difference numerical calculation, other methods. conclusion that goaf’s can be completely stable bear stress is reached. results show depth 1–3 m, maximum accounting for 15% width pillar, 0–3 m; After floor plastic failure, 1–10 3–15 4 times greater than before mining. 22 78.6% spacing. disturbance seam. zone not connected with