Application of Coal Mine Roof Rating (CMRR) to Extended Cuts

Details

• Personal Author:
  Mark C
• Description:
  Since first introduced, the coal mine roof rating (CMRR) has been widely accepted as a tool for geologic characterization and mine planning. This paper discusses the application of the CMRR to another practical ground-control problem: extended cuts. Extended cuts, i.e., cuts greater than 6 m (20 ft) in length, are commonly used with remote-control continuous miners. Extended cuts can greatly increase productivity, but they have been associated with a number of fatal-roof falls. When extended cuts are attempted in weak roof material, the roof may collapse before it can be bolted. Until now, it has not been possible to predict where conditions may not be suitable for extended cuts. In this study, data on the CMRR and extended-cut experience were collected at 36 mines in seven of the United States. It was found that, when the CMRR was greater than 56, deep cuts were routine in nearly every case. When the CMRR was less than 37, extended cuts were almost never taken, and when the CMRR was between 38 and 56, extended cuts were sometimes, but not always, feasible. The data also show that extended cuts are less likely to be stable if either the entry span or the depth of cover increases. [Description provided by NIOSH]
• Subjects:
  Coal Coal Mining Mining Occupational Exposure Occupational Health Safety
• Keywords:
  Coal-miners Coal-mining Ground-control Ground-stability Mine-disasters Mining-equipment Mining-industry Occupational-hazards Traumatic-injuries Underground-mining
• Series:
  Mining Publications
• ISSN:
  0026-5187
• Document Type:
  Text
• Genre:
  Journal Article
• Place as Subject:
  OSHA Region 3 ; Pennsylvania
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  PRL - Pittsburgh Research Laboratory
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  52-56
• Volume:
  51
• Issue:
  4
• NIOSHTIC Number:
  nn:20025245
• Citation:
  Min Eng 1999 Apr; :51(4):52-56
• Federal Fiscal Year:
  1999
• Peer Reviewed:
  True
• Source Full Name:
  Mining Engineering
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:bb8fc2582a71f27176e01f74a067b453fb8fc3b4408e98d678343d012c31be027836c5ee1769ed6419b4b86a812efb535aa577929b777dfbf83a73bf55b2ee7c
• Download URL:
  https://stacks.cdc.gov/view/cdc/220907/cdc_220907_DS1.pdf
• File Type:
  [PDF - 611.02 KB ]