Performance of a novel bump-control pillar-extracting technique during room-and-pillar retreat coal mining. Report of Investigations/1989

Retreat pillar mining concentrates stresses on workings directly out by gob areas, which can result in coal mine bumps. The development of bump-control design criteria by the U.S. Bureau of Mines was furthered by data from a novel bump control mining method at the Olga Mine, McDowell County, WV. The pillar splitting, retreat mining system induced large pillar pressure increases and roof-to-floor convergence. Roof-to-floor convergence monitoring proved to be a valuable tool in evaluating the pillar splitting mining method and localized distressing techniques. Maximum-strain energy storage in chain pillars appears to have occurred just prior to the first of the split cuts. Thus, the pillar-splitting mining method successfully redistributed the weight of the roof away from the pillar line. Shot fire and auger-drilling destressing techniques augmented the pillar-splitting mining method by redistributing the weight of the roof.