Research and application of Gob-Side entry retaining with roof presplitting under residual coal pillar of upper coal seam

In the mining of close coal seam, stress concentration under residual pillar in upper seam leads to serious deformation roadway surrounding rock lower seam. Hence, it poses a huge challenge maintenance entry rock. Based on this, an approach control technology, directional pre-splitting, and roof-cutting pressure relief, was applied. The utilizing pre-splitting relief were studied by numerical simulation field test results indicated that depth achieve 44 m. With application roof presplitting, vertical decreased. Utilizing presplitting with height 7 m angle 15°, gangue filled goaf supported overlying strata. Meanwhile, controlled constant resistance anchor cable (9 length) prevention support structure. Through monitoring, increases rapidly at 30 ∼ 110 behind working face. From 160 m, increased rate gradually slows down tends be stable maximum displacement floor is 511 mm, wall 421 mm. remaining meets demand adjacent