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|When designing pillars in coal and hard rock mines it is necessary to determine the strength of the rock mass forming the pillars. Empirical strength equations, based on rock mass classification techniques, assume that the rock mass is isotropic, this simplification may result in under estimation of pillar strength. Numerical model studies showed that the effect of jointing on pillar strength diminishes as the width to height ratio of a pillar increases. Therefore, the weakening effect of joints should not be equally applied to all pillars regardless of their width to height ratio. The paper presents equations that were developed from laboratory tests on jointed rock samples and numerical models to account for the effects of joint orientation, friction, frequency, and pillar width to height ratio on pillar strength. The equations were calibrated using field data of actual pillar performance in South African coal mines. The method was applied in two case studies in which the strength of jointed coal pillars was assessed and layouts were designed accordingly.|
Additional chapters/articles from the SME-ICGCM book Proceedings 19th International Conference On Ground Control In Mining
|An Approach To Identifying Geological Properties From Roof B||Field Experience Of Measuring The Acoustic Energy From A Ham||Advancements In Reflective Seismic Tomography For The Locati||Longwall Geomechanics, An Australian Perspective||Moonee Colliery: Renewing The Economic Viability Of A Mine U||Successful Application Of Hydraulic Fracturing To Control Wi||Pillar Mining And Longwalling Below Massive Roof Strata: Geo||High Capacity Tensioned Cable Bolts For Tailgate Support||Single Point And Full Scale Laboratory Testing Of Timber Cho||Optimizing Secondary Roof Support With The NIOSH Support Tec||The Use Of Cribless Tailgates In Longwall Extraction||Five Stress Factors Conducive To Bumps In Utah, USA, Coal Mi||Development Of Stress Measurement Techniques In Bump-Prone C||Coal Mine Seismicity And Bumps: Historical Case Studies And||Multi-Scale Assessment Of Coal And Gas Outbursts Based On Fr||Horizontal Stress: The Root Of All Evil?||Utilizing The ?Advance And Relieve? Method To Reduce Horizon||Regional Horizontal Surface Displacements Due To Mining Bene||Prognosis And Control Of Mining Induced Surface Subsidence A||Prediction Of Subsurface Subsidence For Longwall Mining Oper||Development Of A Statistical Technique For Assessing Sandsto||Evaluation Of Surface Subsidence Potential Along A Pipeline||Roof Monitoring In Limestone Mines-Experience With The Roof||Site Characterization For Planning Underground Stone Mines||Potential Problems Related To Mining Under Or Adjacent To Fl||Mine Planning For Longwall And Pillar Retreat Panels Subject||Optimization Of District-Wide Mine Layout In Multi-Seam Mini||Application Of Bolt Design Criteria At Galatia Mine||The Utilization Of Rockbolting Technology And Monitoring Tec||Rockbolting For Highly Stressed Roadways||Evaluation Of Measurement System For Monitoring The Stabilit||Quality Management For Grouted Rockbolts||Evaluating Anchorage Mechanisms Of Fully Encapsulated Rock B||INSTáL CableOx: A New Tensionable & Corrosion Resistant Cabl||Rock Reinforcement Longevity||Progress In The Development Of A Roof Bolt Design Methodolog||Case Studies Of Progressive Pillar Failure In Two Mines Usin||Jointing Effects On Pillar Strength||Impact Of Vertical Stress On Roadway Conditions At Dartbrook||Stepwise Support Technology For Extremely Soft Rock Roadway||Mobile Roof Supports For Pillar Retreat Mining||Three-Dimensional Simulations Of The Roof Behavior In Coal R||Roof Behavior In South African Coal Room And Pillar Panels||Extended Cut Out Distances In Continuous Miner Sections In S||Roof Control Analysis In North River Mine||Analysis Of The Seam Inclination Effect On Roof Stability||The Application Of Rock Mass Classification Principles To Co||Mining Geotechnical Benchmarking||Using The Point Load Test To Determine The Uniaxial Compress||The Influence Of Water Content On Strength Characteristic Of||Polymer Membrane Liners In Underground Coal Mines - Ground C||Applications Of Cement Grouting Method For Controlling Weak||Analysis Of Safety Aspects And Mining Practices For Effectiv|