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|Mine tunnel support using rockbolts was introduced in UK coal mines over the period 1987- 1992 and is now used in over 70% of all mine tunnels. In every case the reinforcement design has been based on the observational approach. After the initial reinforcement design has been established appropriate action levels are defined for predetermined amounts of movement indicating the onset of instability. If the action levels are exceeded appropriate remedial action is taken usually in the form of additional support or reinforcement to maintain stability. This paper outlines the observational design method as used in UK coal mine tunnels. It discusses the low cost instrumentation which has been developed to monitor roof deformation, dual height telltales, how action levels are defined based on the geotechnical environment and the types of remedial measures typically taken. An alternative approach for dealing with areas of increased deformation involves reacting to early roof movement trends and modifying the support installed at the face of the development accordingly. Installation of additional support at the face of the heading improves ground control in poor geotechnical conditions and has the advantage of potentially reducing later additional support costs. A case study is described to illustrate how 'early' action levels can be incorporated into a roof support plan enabling a flexible roof support strategy. Such a system will be site specific and continued analysis of monitored information will be required to confirm the action levels or to adjust them according to any change in geotechnical environment. More accurate roof deformation monitoring systems, such as the Remote Reading Telltale system recently developed by Rock Mechanics Technology Ltd. (RMT) and currently undergoing Mines Safety and Health Administration (MSHA) approval, are ideally suited to this application. The Remote Reading Telltale system provides accurate mine wide monitoring of roof condition on a surface PC.|
Additional chapters/articles from the SME-ICGCM book Proceedings - 18th International Conference on Ground Control in Mining
|Pillar Collapse at Welgedacht Colliery, South Africa: A Case||Causes of Massive Directional Roof Falls in Room and Pillar||Catastrophic Collapse Of Highwall Web Pillars And Preventati||Mine Panel Collapse - Two Case Studies||Roof Geology Mapping In Underground Coal Mines||Electromagnetic Seam Wave Mapping Of Roof Rock Conditions Ac||Geological Conditions At Continuous Miner Sections; Examples||The Role Of Engineering And Geology In Analyzing Ground Cont||The Development And Use Of Risk Assessment Techniques To Ass||Time-Dependent Analysis Of Underground Opening Stability||Tekflex As A Sprayon Screen Replacement In An Underground Ha||Tunnel Deformation Monitoring "Action Levels" In Coal Mines||Skin Failure Of Roof And Rib In Underground Coal Mines||Application Of Polyurethane Injection For Rehabilitation Of||Design Considerations For Bump-Prone Longwall Mines||Design Methodology For Standing Secondary Roof Support In Lo||Modern Shield Technology: Better Than Ever But Still Not Per||Shield Monitoring To Forecast Severe Face Weightings At The||Monitoring Of Longwall Seal Behaviour For Permeability And S||Ground Control In South African Coal Mines - A U.S. Perspect||Rock Mechanics Issues In The Trona Patch||Highwall Augering In Ultra-Thick Western Coal Reserves: Uniq||Seismic Events Due To Underground Mining Activities||Control Technology For Roof Drill Operators||Resin Annulus Size Effects On Rebar Bolt Pull Strength And R||Roof Bolt Response To Shear Stress: Laboratory Analysis||Laboratory Study Of Shear Loading And Bolt Load Transfer Mec||Analysis Of Cable Bolt Performance Using Numerical Modeling||Roof Bolting Application In Longwall Mining In Indonesia And||Ground Control Design For Multiple Seam Mining Using Finite||Pillar Design Issues For Underground Stone Mines||Calibration Of The Analysis Of Longwall Pillar Stability (AL||Mine Convergence When Using Mobile Roof Supports In Pillar R||The Advance And Relieve Mining Method: A Horizontal Stress C||Localized Horizontal Stress And Its Effect On Ground Control||Prediction And Control Of Surface Subsidence Over Abandoned||Effects Of Mining On Underground Infrastructures In The Germ||Ground Deformation In The Case Of Underground Mining Of Thic||Prevention Of Time-Dependent Subsidence By Elimination Of Gr|