Tests of fiber-reinforced shotcrete at the Chief Joseph Mine, Butte, Montana.
Martin-LA; Dunford-JP; MacLaughlin-MM; Cronoble-RR
Trans Soc Min Metal Explor 2007 Dec; 322:61-64
Researchers from the Spokane Research Laboratory (SRL), National Institute for Occupational Safety and Health (NIOSH), in cooperation with engineers from the Department of Mining and Geological Engineering, Montana Tech, Butte, Montana, conducted tests to evaluate the tensile strength, fiber count and adhesion properties of shotcrete applied to round panels and the walls of the mine entry at the Chief Joseph Mine, a research and training facility operated by Montana Tech. The goal of this research was to establish shotcrete application processes that would increase the safety of a mining system by limiting the amount of time that miners are exposed to unprotected roof while also reducing the need for the installation of multiple supports at the advancing face. Testing demonstrated that of the five different fiber dosages the optimal dosage of fibers in the shotcrete for energy absorption is 6.5 kg/m3 (11 lb per cu yd). The best fiber count was obtained with shotcrete applied in a 250-mm (10-in.) square. It was found that additional engineering development was required for the field tests at this research test site. Initial tensile strengths of the round panels were between 30 and 50 kN (6,750 and 11,250 lb). The standard 1 MPa (145 psi) tensile strength was not achieved while conducting these field tests.
Mining-industry; Underground-mining; Ground-control; Control-technology; Engineering-controls; Injury-prevention; Accident-prevention
Transactions of the Society for Mining, Metallurgy, and Exploration