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|This study presents a historic overview of the role of mobile roof support (MRS) technologies in improving stability and worker safety and presents the results of recent field evaluations of the MRS load rate monitoring device and other remote deformation-monitoring techniques. Field studies were implemented at two sites in cooperation among researchers from the National Institute for Occupational Safety and Health (NIOSH), Maleki Technologies, Inc., and J. H. Fletcher & Co. The objective of the field programs were to (l) study the interaction between MRS's and coal mine strata and (2) develop and test suitable monitoring systems for assessing roof and pillar stability. An MRS consists of a roof canopy, four hydraulic cylinders, a caving shield canopy, and associated electromechanical systems mounted on crawler tracks. The machines are controlled by radio from a remote location and operate on self-contained power units. Typically, MRS's have capacities of 5,340 and 7,120 kN (600 and 800 tons). In comparison to posts, an MRS is capable of maintaining the yield load after significant amounts of roof-floor deformation. Because the mining cycle is accelerated, MRS's help reduce the potential for time-dependent roof falls. MRS performance has been monitored in the laboratory under controlled static loading conditions and in the field under deep, two-scam mining conditions. Laboratory studies have quantified support capacity and system stiffness as a function of machine height. Field investigations have focused on determination of optimum operating conditions and development of warning systems that indicate excessive load on the machine and/or impending roof-pillar stability problems. Analyses of field data show that roof instabilities are influenced by (1) pillar failure, (2) pillar yielding, (3) mine seismicity, (4) geologic structures, and (5) panel layout designs and mining practice. Pillar yielding and failure (unloading) and seismicity can be conveniently monitored by the load rate monitoring device, but for consistent detection of roof falls, additional deformation measurements directly within the cuts ate needed.|
Additional chapters/articles from the SME-ICGCM book Proceedings 20th International Conference On Ground Control In Mining
|Hydraulic Fracturing Of Sandstone And Longwall Roof Control||Status Of Longwall Research In CSIRO||Longwall Moves At Twentymile Recovery Mesh System||Risk Assessment Of Geotechnical Factors Associated With Unde||Load And Deflection Response Of Ventilation Stoppings To Lon||The Stress And Failure Paths Followed By Coal Mine Roofs Dur||Simulated Materials Modeling And Analysis Of The Overburden||Sizing Of Final Stumps For Safer Pillar Extraction||Evaluation Of Mobile Roof Support Technologies||FDM Prediction Of A Yield Pillar Performance In Conjunction||Extraction Ratio In Thin Seams Assuring No Surface Subsidenc||Improving Roof Control At A South African Coal Mine||In-Situ Investigation Into The Causes Of Falls Of Roof In So||Failure Characteristics Of Roof Falls At An Underground Ston||Determination Of Limitation Of Roof Layer Separation (LRLS)||The Integration Of Geology And Engineering In Ground Control||Worldwide Implementation Of Continuous Miner System - Integr||Effect Of Face Advance Rates On The Characteristics Of Subsi||The Response Of A High Order Stream To Shallow Cover Longwal||SDPS For Windows: An Integrated Approach To Ground Deformati||Development Of A Remote Reading Dual-Height Telltale System||Enhanced Surface Control For Roof And Rib Support||Long Term Stability Of Mine Workings In Soft Floor Environme||Visualization Of Geostructure By Mechanical Data Logging Of||A Step Towards Understanding The Behaviour Of Wider Roadways||Research And Application Of Combined Reinforcement System||Estimation Of In-Situ Stress At Ikeshima Colliery Using AE A||Typical Complete Stress-Strain Curves Of Coal||Analysis Of Roof Bolt Systems||Effects Of Bedding Plane Sliding And Separation And Tensione||Systems Used In Coal Mining Development In Long Tendon Reinf||Determination And IT-Supported Evaluation Of Rock Mechanical||Tensioned Cable Bolts As Primary Support: Update||Determination Of Basis For The Double Use Of Rectangular Roc||Cost Preventive System To Control Unstable Roof In Main Line||Injection Techniques for Cost-effective Stabilization of Bri||An Analysis of Rock Failure Around a Deep Longwall Using Mic||Numerical Simulation on Microseismicity Due to Mining at One||Investigation of Seismicity Near Appin, NSW, and its Associa||Effects of Bolt Spacing, Bolt Length, and Roof Span on Bolt||Evaluation of Instrumented Cable and Rebar Bolts as Ground S||Application of the Coal Mining Roof Rating System in South A||Roof Instability Rating (RIR) System and Its Application at||Updating the NlOSH Support Technology Optimization Program (||Mistakes, Misconceptions, and Key Points Regarding Secondary||Non-Destructive Testing on Fully Grouted Rockbolts||Visual Recognition of the Load of Roof-Bolts by an Indicator||A New Rockbolt Axial Load Measuring Device||A New Approach to the Integrity Testing of Ground Anchorages||A Lineament Analysis Case Study of the Fola Coal Co., LLC. N||Analyses of Valley Fill Slope Stability - Three Case Studies||Modeling of Joint and Fracture Distributions in Rock Mass Be|