If you have access to OneMine as part of a member benefit, log in through your member association website for a seamless user experience.
|Discussion on the design of roof support in tailgates has often been conducted without a clear statement of the stress and failure conditions acting. There is general agreement that in the tailgate the vertical stresses above the chain pillar increase. Within the stress 'bulb' associated with this vertical stress increase there will be an increase in horizontal stress. This does not mean that the horizontal stresses acting across the roof line increase. In retreat longwalling, the proximity of the tailgate to the adjacent goof results in a substantial reduction in the horizontal stress field acting in the immediate roof. Furthermore, at the face/tailgate corner the onset of significant compression of the chain pillar. if it is designed to yield, will result in a further reduction in the horizontal stresses in the immediate roof. It is suggested that this latter mechanism can cause the horizontal stresses in the immediate roof to go to zero. Whatever, the horizontal stress acting across the roof in the face/tailgate corner will be significantly lower than in the face/maingate corner. The implication of the model is that support design in tailgates should be based on the assumption of zero horizontal (in fact tensile) stresses. How the roof behaves in a tensile stress environment is a function of joint spacing and orientation compared to excavation width and direction. It is speculated that the empirical relationship between support density and roof rating results from the relationship between joint spacing and bedding spacing. The onset of stress reductions has major implications to the design of cable and bolt anchorages in the tailgate environment.|
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|