Skip directly to search Skip directly to A to Z list Skip directly to page options Skip directly to site content

NIOSHTIC-2 Publications Search

Search Results

A study of the ground control effects of mining longwall faces into open or backfilled entries.

Authors
Oyler-DC; Mark-C; Dolinar-DR; Frith-RC
Source
Geotech Geol Eng 2001 Jan; 19(2):137-168
NIOSHTIC No.
20021827
Abstract
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.
Keywords
Coal-mining; Rock-falls; Case-studies; Mine-shafts; Mine-workers; Miners; Mining-industry; Mining-equipment; Engineering-controls; Engineering; Weight-factors; Weight-measurement
Contact
Pittsburgh Research Laboratory, National Institute for Occupational Safety and Health, Pitssburgh Research Laboratory P.O. Box 18070, 626 Cochrans Mill Road, Pittsburgh PA, USA
CODEN
GGENE3
Publication Date
20010101
Document Type
Journal Article
Fiscal Year
2001
NTIS Accession No.
NTIS Price
Issue of Publication
2
ISSN
0960-3182
NIOSH Division
PRL
Source Name
Geotechnical and Geological Engineering
State
PA
TOP