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A flexible helical rock bolt.
Denver, CO: U.S. Department of the Interior, Bureau of Mines, RI 8300R, 1978 Jan; :1-26
This report describes the results of Bureau of Mines laboratory and preliminary field tests on a rock bolt of helical shape. The flexible construction allows the bolt to maintain a more stable load level than is possible with a straight bolt. Bolt load changes resulting from anchor slippage, blasting shock, or changes in mine geometry with mining advance are minimized. Preliminary field tests were performed at the Kaiser Steel York Canyon Mine where the load changes of straight and helical bolts were measured using a vibrating-wire load gage. The field tests were performed to establish the viability of the concept of a helical bolt. The practical usefulness in terms of performance and economics remains to be shown. The change in bolt load for the flexible bolts was one- third that for the straight bolts. There were no malfunctions of the gage, and the bolts maintained a more uniform load than the straight bolts used as controls.
Mining-industry; Underground-mining; Ground-control; Ground-stability; Mining-equipment; Engineering-controls
IH; Report of Investigations
NTIS Accession No.
Denver, CO: U.S. Department of the Interior, Bureau of Mines, RI 8300R
Page last reviewed: April 12, 2019
Content source: National Institute for Occupational Safety and Health Education and Information Division