If you have access to OneMine as part of a member benefit, log in through your member association website for a seamless user experience.
|A study of rock support interaction mechanics was conducted by the U.S. Bureau of Mines at the Jim Walter Resources No. 7 Mine, Brookwood, AL. Bolt loads and entry deformation were monitored at four sites in a tailgate roadway. Two sites were areas supported by fully grouted resin bolts, and two sites were supported by tensioned bolts that used resin-assisted mechanical anchors. The yield capacity of the tensioned bolts was 37 pct higher than that of the grouted bolts. To monitor loads, instruments were mounted on 16 bolts, which were installed during entry development in the standard bolt pattern. Additional instrumented bolts were installed as supplemental support just prior to the headgate pass of the first longwall. Instruments to measure roof movements included three-point roof extensometers and convergence stations. Readings were taken during section development and as each longwall panel passed the test area. The fully grouted bolts showed localized loads that were higher than loads on the tensioned bolts; however, overall loading magnitudes were similar. Many sections of the fully grouted bolts passed the yield point of the bolt steel (98 kN or 22,000 lb). However, the maximum strain measured at any loca¬tion was 50 pct of the ultimate strain, and there was adequate bolt length to transfer the high loads into the rock. Significant bending was detected at many points along the length of the bolts and seemed to be the most significant mechanism in support-rock interaction. Loads on the tensioned bolts did not exceed the yield point of 160 kN (35,000 lb). Entry deforma¬tion, supplemental bolt loading, and general entry degradation appeared to be slightly less at the tensioned bolt sites. Local geology and in situ horizontal stress were also observed to affect con¬ditions at the test sites.|
Additional chapters/articles from the SME-ICGCM book Proceedings of 12th International Conference on Ground Control in Mining
|Bolting Practice In Longwall Gateroads At The Miike Colliery||Cable Supports For Improved Longwall Gateroad Stability||Comparisons Of Active Versus Passive Bolts In A Bedded Mine||Flexibolt Flexible Roof Bolts: A New Concept For Strata Cont||The Design And Application Of Hercules Cribs For Underground||Cyprus Shoshone Tailgate Roof Control: Case Study||Engineering Methods For The Design And Employment Of Wood Cr||The Use Of Foamed Cement Cribs At American Electric Power Fu||A Comparison Of Support Reactions To Retreat Longwall Front||Entry Design For Optimum Stability In A Multi-Seam Environme||Gate Entry Design For Longwalls Using The Coal Mine Roof Rat||A Test Of Predictive Numerical Models To Simulate Entry Desi||The Coal Mine Roof Rating (CMRR) A Practical Rock Mass Class||Comparative Analysis Of Longwall Gateroad Designs In Four De||Further Improvements In The Roof Beam Tilt Method Of Gateroa||Application Of A Static And Geophysical Monitoring System Fo||Flexible Support Design For Gateroads Of Retreating Longwall||Longwall Support Monitoring||Case Studies Using Mine-Wide Monitoring Systems For Geotechn||An Application Of Tree Classification Method In Analysis Of||Image Analysis Development And Application To Fracture Patte||Mathematical Modeling Of Strong Roof Beds In Longwall Mining||Load Deformation Behavior Of Simulated Longwall Gob Material||Monitoring Of The Interaction Effects Over A Longwall Panel||Design, Monitoring And Evaluation Of A Pre-Driven Longwall R||Ground Control And Safety Considerations During Longwall Rec||Utilization Of Polymer Grid Structures In Shield Recovery Op||The Impact Of Variability In Coal Strength On Mine Planning||Underground Application Of Optimization||Modern Geotechnical Exploration And Mine Design||A New Method For Longwall Pillar Design||A Rock Mass Strength Concept For Coal Seams||Techniques To Increase Yield Pillar Residual Strength||Application Of Seismic Tomography For Assessing Yield Pillar||Structure, Strength And Relaxation Of Interbuden For Input I||Rock Compaction Caused By Dewatering In Poorly- Consolidated||Correlation Between The Effect Of Confining Pressure On Comp||Characterization Of Structural Integrity And Stress State Vi||Rock Mechanics Property Data Bank For Coal Measure Strata||Failure Modes Of Mine Tunnels In Stratified Rock Structures||Determination Of Plate Size Effect On Ultimate Bearing Capac||Development And Evaluation Of A Floor-Bearing Capacity Test||Investigation Of Blast Damage And Underground Stability||Development Of A Slope Stability Program For Improved Quarry||Material Instability Hazards In Mine Processing Operations||Mine Design Considerations For Surface Subsidence Control||Surface Fracture Development From Mine Subsidence In Eastern||An Integrated Approach To Subsidence Modelling And Predictio||Effect Of High-Extraction Coal Mining On Surface And Ground||Economic Evaluation Of Subsidence Damage Mitigation Techniqu|