Monitoring of reinforced cemented backfill in an underhand stope.
Williams TJ; Denton D; Peppin C; Bayer D
Pacific rocks 2000: rock around the rim--proceedings of the Fourth North American Rock Mechanics Symposium, NARMS 2000, Seattle Washington, July 31-August 3, 2000. Girard JM, Leibman M, Breeds C, Doe T, eds. Brookfield, VT: A.A. Balkema, 2000 Jul; :387-393
Hecla Mining Company and NIOSH cooperated in a study to monitor reinforced cemented backfill at Hecla's Lucky Friday Mine in Mullan, ID. An instrumentation plan was developed to identify loads on rock bolts installed to reinforce the cemented backfill, determine the engineering properties of the backfill, and measure the amount of stope waIl closure. Data collected as three successive cuts were mined under the instrumented backfill showed stope waIls converged on the backfill, inducing loads up to 3450 kPa in the fill. The backfill deformed against the top and bottom plates of the bolts, producing loads to 177 kN on the bolts. We theorize that a compressive zone was created in the backfill, allowing the backfill to remain stable as long as the zones from adjacent bolts overlapped. Understanding the mechanics of the backfill system is crucial to ensuring the safety of miners working under backfill.
Rock mechanics; Stope mining; Underground mines; Underground mining; Mining industry
T. Williams, Spokane Research Laboratory, National Inititute for Occupational Safety and Health, WA, United States
Girard JM; Leibman M; Breeds C; Doe T
Pacific rocks 2000: rock around the rim--proceedings of the Fourth North American Rock Mechanics Symposium, NARMS 2000, Seattle Washington, July 31-August 3, 2000