Mining Publication: Deep Cover Pillar Extraction in the U.S. Coalfields
Original creation date: August 2002
Deep cover retreat mining (overburden in excess of 750 ft) is an important emerging issue which will intensify in the future as the more easily mined shallow seam reserves are depleted. Analysis of Mine Safety and Health Administration (MSHA) statistics indicates that deep cover pillar recovery accounts for a disproportionate share of the underground coal mine roof/rib fall fatalities and injuries. Past research has shown that previously recommended Analysis of Retreat Mining Pillar Stability (ARMPS) stability factors (SF's) may be excessive for deep cover pillar design. The objectives of this study were to evaluate the various methods and strategies by which panels, production pillars and barrier pillars are developed and extracted under deep cover, and to develop appropriate design guidelines. In the course of the research, 29 mines in 7 states were investigated to collect panel design case histories. At each mine site, underground geotechnical data were collected on the pillar line in order to document roof rock, coalbed and floor conditions. The analyses indicated that squeezes were the most likely failure mode where the depth was less than 1,250 ft, but bumps predominated in the deeper cover cases. Immediate roof rock quality, the ARMPS SF's, and barrier pillar stability factors were all found to be important parameters in determining the outcomes of the case histories. Design guidelines, including suggestions for barrier pillars to isolate active panels from nearby gobs in bump prone ground, are also proposed.
Authors: FE Chase, C Mark, KA Heasley
Conference Paper - August 2002
NIOSHTIC2 Number: 20023127
In: Peng SS, Mark C, Khair AW, Heasley KA, eds. Proceedings of the 21st International Conference on Ground Control in Mining. Morgantown, WV: West Virginia University, 2002 Aug; :68-80
See Also
- ARMPS - Analysis of Retreat Mining Pillar Stability - 6.2.02
- Coal Mine Bumps: Five Case Studies in the Eastern United States
- Deep Cover Pillar Recovery in the US
- Optimum Mine Designs to Minimize Coal Bumps: A Review of Past and Present U.S. Practices
- Pillar Design and Strategies for Retreat Mining
- Proceedings: New Technology for Ground Control in Retreat Mining
- Research Report on the Coal Pillar Recovery Under Deep Cover
- The State-of-the-Art in Coal Pillar Design
- Technology News 464 - Analysis of Retreat Mining Pillar Stability (ARMPS): Version 4.0 for Windows
- Technology News 516 - ARMPS-HWM: New Software for Sizing Pillars for Highwall Mining
- Page last reviewed: 3/13/2017
- Page last updated: 3/13/2017
- Content source: National Institute for Occupational Safety and Health, Mining Program