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|The fundamental problems associated with ground control reflect the inability of mining personnel to "see" the development of anomalous conditions. Toward this end, the U. S. Bureau of Mines is investigating the application of seismic refraction tomography for imaging the process of pillar yielding, at the Foidel Creek coal mine, near Steamboat Springs, CO. The inherent three-dimensional problem of imaging coal pillar stress is reduced to a single plane by considering only the stress transmitted from the pillar to the adjacent floor rock. This approach exploits the fact that refracted seismic energy is essentially confined to the adjacent higher velocity sandstone strata. The tomographic analysis using ray-tracing based on wavefront migration resulted in a robust P-wave tomogram from which regions of high velocity indicate zones of high stress concentration, whereas low velocity zones indicate regions of stress relief. The interpreted region of high stress concentration occurs at the pillar end nearest to the working face of the adjacent longwall panel. This finding is corroborated by vertical pressure cell measurements recorded in the pillar. The stress diminishes toward the pillar perimeter with local minima correlating to the locations of observed pillar spalling. Time-sequence monitoring, as the longwall face advances, is recommended for evaluating changing stress conditions.|
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|