Study of optimum dimensioning of abutment pillars in longwall mining of GL(I)over-dot Tuncbilek Coal Mine

In this study, optimum dimensioning of abutment pillars between the adjacent panels in retreat longwall mining method with sublevel caving applied to the 7 m thick in average coal seam of GLI Tuncbilek Coal Mine, located in west part of Turkey, has been tried to be achieved. Convergence measurements at four stations in the roadways have shown severe displacements due to mining the thick coal seam with sublevel caving and the inadequate abutment pillar (rib pillar) left in 15 m width between the mined out and extracting panels. Measurement of load on roadway supports has proved that the increase of load related to the distance fi om the longwall face caused the increase of convergence in the roadway. Several models with different pillar widths have been studied using the boundary element program of Mulsim. The model with 30 m pillar width has shown the stable conditions in the roadway and pillar. In this study it is suggested that, instead of applying large abutment pillars between adjacent panels, filling the roadway of the mined out panel with cemented fill and then leaving a protective pillar with a width of 5 meters for the new panel would be the best solution to provide stability in the roadway of the new (extracting) panel and also provide minimum amount of coal losses due to the pillar witdh.