Researchers from the National Institute for Occupational Safety and Health (NIOSH) Spokane Mining Research Division (SMRD) are evaluating the comparative performances of shotcrete support systems currently utilized in underground metal mining. The SMRD Metal Ground Control Team in Spokane, Washington USA, is exploring applications of photogrammetry for visual performance assessment of shotcrete reinforcement utilized in a support system. This paper describes how photogrammetry is being used to correlate support deformation with remaining support system capacity in laboratory tests. These systems include various types of shotcrete reinforcement (fibers, wire meshes) and bolts. This study demonstrates how different installation sequences (i.e., mesh/bolts/shotcrete versus shotcrete/mesh/bolts) affect the support capacity of the system. Quasi-static, high energy, high deformation tests were performed for six different sequencing scenarios. This research supplements previous studies into photogrammetric and laser scanning methods, and enhances how shotcrete reinforcement system deformation may be understood to maximize miner safety. NIOSH SMRD is committed to improving the health and safety of miners through innovative research and applications of technology.

Ground control testing

Underground metal mines typically use a combination of rock bolts, wire-mesh, and shotcrete to support excavations. While good rock bolt performance is essential to successful ground control, the containment and support of the ground between the bolts is equally important. Shotcrete and mesh, in various combinations and with other components, are often used to provide this support, and thus combine with the rock bolts to form an overall shotcrete support system. Understanding how these systems respond to induced stresses is therefore required for successful ground control planning. However, the order in which the system components are installed may differ depending on a variety of factors, and the resulting performance of identical systems, in terms of components, may also differ. The current study accounts for the differing expectations of these shotcrete support systems depending on the order of system component installation, and how deformation-based monitoring of these shotcrete systems can be used to assess performance.

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