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|Researchers from the U.S. Bureau of Mines conducted a field study to assess the safety of remotely controlled mobile roof supports (MRS) in a retreat pillar mining operation, Data were collected to provide the Mine Health and Safety 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 and were monitored to obtain information on entry stability. Pressure transducers and string pots were installed on all four MRS's to obtain loading and displacement information. and 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 in load when the MRS's were set and increases 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 I and 2 usually had the higher loads, with these loads increasing as the pillars on each side were being mined. MRS 3 normally had lower loads than I 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.|
Additional chapters/articles from the SME-ICGCM book Proceedings of 14th International Conference on Ground Control in fining
|Truss Systems For Longwall Tailgate Support - Update||Cable Support Systems For Longwall Gate Road Stability||Innovative Tailgate Support For Heavy Ground: 11 Left Longwa||Parameters Affecting Resin-Anchored Cable Bolt Performance:||Roof Support Performance In High Stress Conditions||Regional Horizontal Stress And Its Effect On Longwall Mining||Deformation Development Around Mine Roadways And Simulation||Monitoring Mobile Roof Supports||Analysis Of Retreat Mining Pillar Stability||Planning And Design For Barrier Pillar Recovery Three Case H||Influence Of Partings In A Coal Seam On Long Term Pillar Sta||A Cooperative Study Of Gate Entry Designs Welbeck Colliery (||Comparative Case Study Of Yielding And Critical Coal Pillar||Comparison Of Empirical, Analytical, And Numerical Methods O||Nonlinear Approach For Determining Design Criteria For Yield||In-Situ Coal Strength Determination - Case Studies||The Design And Application Of Propsetter? In Underground Coa||Renewed Interest In Prop Supports As A Replacement For Wood||Improved Intersection Design And Monitoring In The Sydney Co||Drivage System In Retreat Longwall Gateroad||Case Study Of Stability Investigations Related To Shallow Un||Analysis Of Rockbolt Performance At The Waste Isolation Pilo||Continuous Improvement In Cuttable Coal Rib Support In Austr||Floor Failure Induced By Lateral Stress Ahead Of Longwall Su||Towards A Method Of Determining Floor Quality In An Undergro||Chinese And North American High-Extraction Underground Coal||Integration Of CAD-Based Mine Planning And Subsidence Engine||Development Of A Subsidence Database And Determination Of Su||Statistical Regional Calibration Of Subsidence Prediction Mo||Subsidence Monitoring Results, Thick Seam Longwall Mining In||Application Of Mechanical And Groundwater-Flow Models To Pre||The Application Of Underground In-Seam Seismic Methods (UISS||Vertical Stress Redistribution Around A Retreating Longwall||Entry Stability Monitoring & Analysis For Longwall & Continu||A Case Study Of A Deformation Mechanism Around A Two-Entry G||Multiseam Mining On South African Collieries||Design And Planning Of Lower Seam Longwall Gateroads||Optimizing Pillar Design In A Multi-Seam Environment|