Field performance testing of fully grouted roof bolts.
Mark-C; Compton-CS; Dolinar-DR; Oyler-DC
Trans Soc Min Metal Explor 2004 Jan; 316:1-6
More than 80% of roof bolts in the United States are fully grouted, but about 1,500 roof falls are reported each year. Anchorage failure of a fully grouted bolt can occur when the roof is active near the top of the hole. This paper reports on an extensive series of short-encapsulation pull tests in which the bolts are installed with only 0.3 m (1 ft) of resin. The tests were conducted in the NIOSH's Safety Research Coal Mine at Bruceton, PA, and in operating mines in West Virginia and Pennsylvania. The tests confirmed that poor anchorage could be encountered under some weak rock conditions. Suggestions for anchorage improvement are included.
Mining-industry; Underground-mining; Coal-mining; Ground-control; Ground-stability; Safety-research; Injuries; Hazards; Rock-falls
NIOSH Pittsburgh Research Laboratory, P.O. Box 18070, Pittsburgh, PA 15236
Transactions of the Society for Mining, Metallurgy, and Exploration