Monitoring mobile roof supports.
Hay-KE; Signer-SP' King-ME; Owens-JK
Proceedings: New Technology for Ground Control in Retreat Mining, Pittsburgh, PA: National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 97-133, IC 9446, 1997 Mar; :89-98
Researchers from the Spokane Research Center conducted a field study to assess the safety of remotely controlled mobile roof supports (MRS' s) in a retreat pillar mining operation. Data were collected to provide the Mine Safety and Health Administration with criteria needed to develop guidelines for MRS use and to determine if precursors could be identified that would alert miners to imminent roof falls. Two test sites at which two different support methods-MRS's and posts-were used were monitored to obtain information on entry stability. Pressure transducers and string potentiometers were installed on all four MRS's to obtain loading and displacement information. Roof bolt load cells, sonic probes, extensometers, and survey targets were installed in the surrounding entries to obtain information on ground behavior. Results showed a larger increase in roof bolt loading and roof movement when MRS's were used, especially in the intersection area. Roof bolt loads in the entries showed decreases when the MRS's were set and increases of up to 11.1 kN (2,500 lbf) when the MRS's were unloaded. Unloading of one MRS in a pair did not significantly increase load on the other. MRS's 1 and 2 usually had the higher loads; these loads increased as the pillars on each side were being mined. MRS 3 normally had lower loads than 1 and 2; however, it also experienced some very high loads when in the last position near the pushout. MRS 4 usually had the lowest loads, primarily because it was located near the solid pillar that was not being mined.
Mining-industry; Underground-mining; Accident-prevention; Coal-mining; Mining-equipment; Injury-prevention
Proceedings: New Technology for Ground Control in Retreat Mining