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|The objective of extensive underground experimentation on three longwall coal faces was to improve the stability of mechanised longwall faces through investigation of the relations between support resistance and convergence and resultant deformation of roof and face strata. In particular the influence of high setting and yield pressures on several strata and support parameters was studied in great depth. Increased setting pressures resulting in an increase in setting load densities from 0.15 MN/m2 to O.45 MN/m2 were shown to reduce convergence, face spalling roof flaking, lateral movement of roof and floor, extrusion of the face wall and progressive failure of the coal wall ahead of the face. This was shown to result mainly from the change in roof strata deformation from a wedge shaped compression zone with tension at the face edge to an even beam shaped compression zone over the face area. Debris thickness above the support canopy and below the base was observed to be the one of the most variable parameters which influenced the support characteristics particularly the rate of load acceptance by supports and the roof to floor convergence. A setting load density of 0.4 MN/m2 to 0.5 MN/m2 was found to be optimum under soft to moderately strong sandstone roofs. The authors demonstrated that use of guaranteed set valves with powered supports contribute to good strata control, reduce face down-time and increase face productivity.|
Additional chapters/articles from the SME-ICGCM book Proceeding of the Fourth Conference on Ground Control in Mining (ICGCM)
|Truss Bolting On-Cycle in Jane Mine Lower Freeport Seam||Design Of A Roof Truss Bolting Plan For Bear Mine||Tension-Torque Relationship For Mechanical Anchored Roof Bol||A Novel System For Automatic Installation Of Cement Grouted||Load Transfer Mechanics In Fully-Grouted Roof Bolts||An Investigation Of Longwall Pillar Stress History||Impact Of Horizontal Load On Shield Supports||Interaction Between Roof And Support On Longwall Faces With||Roof Control With Polyurethane For Recovery Of Kitt Energy?s||First Caving And Its Effects--A Case Study||Staubbekampfung An Schildausbau In Bruchbaustreben (Combatin||Yield Pillar Applications--Impact On Strata Control And Coal||Constraint Is The Prime Variable In Pillar Strength||Massive Pillar Failure--Two Case Studies||Investigations Of Underground Coal Mine Bursts||Destressing Practice In Rockburst-Prone Ground||Statistical Characterization Of Coal-Mine Roof Failure: Sugg||Pillar Design - Continuous Miner Butt Section And Longwall D||Design Factors In Near-Seam Interaction||Remote Sensing For Roof Control And Mine Planning: An Overvi||Design, Construction And Performance Of A Single Pass Lining||Computer Modelling And In Situ Instrumentation Techniques: A||A Sonic Wave Attenuation Technique For Monitoring Of Stress||The Radio Imaging Method (RIM) -- A Means Of Detecting And I||Clay Veins: Their Physical Characteristics. Prediction, and||Evaluation of the Point Load Strength for Soft Rock Classifi||Ground Control Experiences in a High Horizontal Stress Field||Horizontal Stresses and Their Impact on Roof Stability at th||Ground Control Problem Associated with Longwall Mining of De||Geotechnical Aspects of Subsidence over Room and Pillar Mine||Proposed Criteria for Assessing Subsidence Damage to Surface||Surface Subsidence. in Longwall Mining--A Case Stud||An Integrated Approach to the Monitoring and Modeling of Gro|