Analysis of retreat mining pillar stability (ARMPS).
Proceedings: New Technology for Ground Control in Retreat Mining, Pittsburgh, PA: National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 97-133, IC 9446, 1997 Mar; :17-34
The prevention of pillar squeezes, massive pillar collapses, and bumps is critical to safe pillar recovery operations. To help prevent these underground safety problems, the Pittsburgh Research Center has developed the Analysis of Retreat Mining Pillar Stability (ARMPS) computer program. ARMPS calculates stability factors (SF) based on estimates of the loads applied to, and the load-bearing capacities of, pillars during retreat mining. The program can model the significant features of most retreat mining layouts, including angled crosscuts, varied spacings between entries, barrier pillars between the active section and old (side) gobs, and slab cuts in the barriers on retreat. It also features a pillar strength formula that considers the greater strength of rectangular pillars. The program may be used to evaluate bleeder designs, as well as active workings. A data base of 140 pillar retreat case histories has been collected across the United States to verify the program. It was found that satisfactory conditions were very rare when the ARMPS SF was less than 0.75. Conversely, very few unsatisfactory designs were found where the ARMPS SF was greater than 1.5. Preliminary analyses also indicate that pillar failures are more likely beneath sandstone roof and that the ARMPS SF may be less meaningful when the depth of cover exceeds 230 m (750 ft).
Mining-industry; Underground-mining; Accident-prevention; Mathematical-models; Coal-mining
Proceedings: New Technology for Ground Control in Retreat Mining