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Mining Publication: A Study of the Ground Control Effects of Mining Longwall Faces Into Open or Backfilled Entries
Keywords: Longwall mining Roof falls Support design and selection
Original creation date: January 2001
Authors: DC Oyler, C Mark, DR Dolinar, RC Frith
Peer Reviewed Journal Article - January 2001
Download PDF Document (1.46 MB)
NIOSHTIC2 Number: 20021827
Geotech Geol Eng 2001 Jan 19(2):137-168
Unusual circumstances may require that a longwall retreat into or through a previously driven room. The operation can be completed successfully, but there have been a number of spectacular failures. To help determine what factors contribute to such failures, a comprehensive international database of 131 case histories has been compiled. The cases include six failures where major rock falls occurred in front of the shields, and seven even more serious failures involving major overburden weighting. The case studies suggest two types of room failure mechanism. The first is a roof fall type failure caused by loading of the immediate roof at the face as the fender or remnant longwall panel narrows. The second is an overburden weighting type failure caused by the inability of the roof to bridge the recovery room and face area, and affecting rock well above the immediate roof. The data indicate that the roof fall type of failure is less likely when intensive roof reinforcement (bolts, cables and trusses) is employed together with higher-capacity shields. The overburden weighting failures, in contrast, occurred when the roof was weak and little standing support was used. Weighting failures were not greatly affected by the density of roof reinforcement. In one of the overburden weighting cases, in a Pittsburgh coalbed mine, stress cell, convergence, bolt load and extensometer data have been used to analyze the failure in detail.
Image of publication A Study of the Ground Control Effects of Mining Longwall Faces Into Open or Backfilled EntriesPeer Reviewed Journal Article - January 2001
Download PDF Document (1.46 MB)
NIOSHTIC2 Number: 20021827
Geotech Geol Eng 2001 Jan 19(2):137-168
See Also
Creep Along Weak Planes in Roof and How It Affects Stability
Development and Application of the Coal Mine Roof Rating (CMRR)
Diagnosing and Controlling Moisture-Sensitive Roof in Coal Mines
The Introduction of Roof Bolting to U.S. Underground Coal Mines (1948-1960): A Cautionary Tale
Mistakes, Misconceptions, and Key Points Regarding Secondary Roof Support Systems
Optimizing Secondary Roof Support with the NIOSH Support Technology Optimization Program (STOP)
Overview of Coal Mine Ground Control Issues in the Illinois Basin
Performance Characteristics for Welded Wire Screen Used for Surface Control in Underground Coal Mines
Preventing Falls of Ground in Coal Mines With Exceptionally Low-Strength Roof: Two Case Studies
Preventing Injuries Caused by Unrecognized Stone Mine Roof Beam Failures With a Pro-Active Roof Control Plan
Page last reviewed: September 21, 2012
Page last updated: September 21, 2012
Content source: National Institute for Occupational Safety and Health, Mining Program
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