Geotechnical Considerations for Concurrent Pillar Recovery in Close-Distance Multiple Seams

Details

• Personal Author:
  Zhang P
• Description:
  Room-and-pillar mining with pillar recovery has historically been associated with more than 25% of all ground-fall fatalities in the underground coal mines of the United States. The risk of ground falls during pillar recovery increases in multiple-seam mining conditions. The hazards associated with pillar recovery in multiple-seam mining include roof cutters, roof falls, rib rolls, coal outbursts, and floor heave. When pillar recovery is planned in multiple seams, it is critical to properly design the mining sequence and panel layout to minimize potential seam interaction. This paper addresses geotechnical considerations for concurrent pillar recovery in two coal seams with 70 ft of interburden under about 1,000 ft of depth of cover.The study finds that, for interburden thickness of 70 ft, the multiple seam mining influence zone in the lower seam is directly under the barrier pillar within about 100 ft from the gob edge of the upper seam. The peak stress in the interburden transfers down at an angle of approximately 20 degrees away from the gob, and the entries and crosscuts in the influence zone are subjected to elevated stress during development and retreat. The study also suggests that, for full pillar recovery in close distance multiple seam scenarios, it is optimal to superimpose the gobs in both seams, but it is not necessary to superimpose the pillars. If the entries and/or crosscuts in the lower seam are developed outside the gob line of the upper seam, additional roof and rib support needs to be considered to account for the elevated stress in the multiple seam influence zone. [Description provided by NIOSH]
• Subjects:
  Mining Occupational Health Safety
• Keywords:
  Analytical Models Coal Mines Coal Seams Environmental Stress Environmental Technology Geologic Models Geotechnical Engineering Ground Control Ground Falls Ground Monitoring Ground Stability Load Monitoring Mathematical Models Pillar Design Pillar Mechanics Retreat Mining Rock Mechanics Roof Falls Roof Supports Room And Pillar Mining Safety Research Strata Control Stress Stress Analysis Underground Mines

  More +
• Series:
  Mining Publications
• ISBN:
  9780873354561
• Publisher:
  Society for Mining, Metallurgy & Exploration
• Document Type:
  Text
• Genre:
  Proceedings
• Place as Subject:
  OSHA Region 3 ; Pennsylvania ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  PMRD - Pittsburgh Mining Research Division
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  76-84
• NIOSHTIC Number:
  nn:20050360
• Citation:
  Proceedings of the 36th International Conference on Ground Control in Mining, July 25-27, 2017, Morgantown, West Virginia. Mishra B, Lawson H, Murphy M, Perry K, eds. Englewood, CO: Society for Mining, Metallurgy & Exploration, 2017 Jul; :76-84
• Contact Point Address:
  Peter Zhang, Mining Engineer, Ground Control Branch, NIOSH, Pittsburgh Mining Research Division, Pittsburgh, PA
• Editor(s):
  Mishra B; Lawson H; Murphy M; Perry K
• Federal Fiscal Year:
  2017
• NORA Priority Area:
  Mining
• Peer Reviewed:
  False
• Source Full Name:
  Proceedings of the 36th International Conference on Ground Control in Mining, July 25-27, 2017, Morgantown, West Virginia
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:7fe0bf3a18a9668e50fe027fe4c96bf8138eb9c81bacaf74a89efa9bbeaae4b9e11c53653c964fe96b4b2be7afbbc8b3d8ca4e0555bf185e04bb1d6c2c7b2889
• Download URL:
  https://stacks.cdc.gov/view/cdc/227549/cdc_227549_DS1.pdf
• File Type:
  [PDF - 41.15 MB ]