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|A massive pillar collapse occurs when undersized pillars fail and rapidly shed their load to adjacent pillars which in turn fail. This chain reaction-like failure may involve hundreds, even thousands, of pillars and the consequences have been catastrophic. One effect of a massive pillar collapse can be a powerful, destructive, and a potentially hazardous airblast. On eleven recent occasions, massive pillar collapses have occurred in six southern West Virginia coal mines. Two other instances of massive pillar collapses in U.S. mines have been documented in the literature. Research was conducted at four mines where massive pillar collapses occurred. Geotechnical evaluations of roof rock, coalbed, and floor conditions were made. Evidence indicates that in each case a massive and competent roof rock unit was able to bridge a relatively wide span, creating a pressure arch. Eventually, the pressure arch apparently broke down, and the structural characteristics of the pillar system were such that sudden, massive pillar failures occurred. Data collected at the failure sites also indicates that all the massive collapses occurred where the pillars width-to-height ratio was 3.0 or less. Numerical modeling, performed with a modified version of the MULSIM/NL computer program, supports the conclusions that the extent of the mined-out area, the bridging capability of the main roof, and the width-to-height ratio of the pillars are probably all significant factors in the occurrence of massive pillar failures.|
Additional chapters/articles from the SME-ICGCM book Proceedings of 13th International Conference on Ground Control in Mining
|Cable Bolting - Potential Applications For Variable Strata C||Evaluation Of Support Performance In A Highly Stressed Mine||Operational Experience With FLEXIBOLT Systems In Australian||Roofbolting In The Cape Breton Development Corporation'||Some Factors Influencing Stability Of Longwall Gateroad||Design Of Roadway Support Using A Strain Softening Model||Automation Of A Progressive Failure Procedure For Analysis O||The Massive Collapse Of Coal Pillars - Case Histories From T||Time Dependent Strength Of Coal Strata For Long-Term Pillar||Yield Pillar Behavior At Jim Walter No. 7 Mine Stress And St||A Comparison Of Overburden Response Due To Longwall Mining||Longwall Ground Behavior Characteristics In The Illinois Coa||Cavability Study Of A Competent Roof - A Case Study||Roof Pressure Monitoring Using The Integrated Longwalt Autom||Longwall Production, Maintenance, And Roof Control System||The Design And Selection Of Powered Supports For Application||Tailgate Support Practice In U.S. Longwall Mines - A Survey||Influence Of Support Capacity And Geometry On Tailgate Suppo||Innovative Concept In Tailgate Entry Support: Elimination Of||Resin-Grouted Cables For Longwall Tailgate Support Stability||Tailgate Roadway Convergence: A Key Indicator Of Potential G||Assessment Of Wood And Alternative Materials For Supplementa||Experience With The Boundary Element Method Of Numerical Mod||The Fault At The End Of The Tunnel||Microseismic Monitoring In The Sydney Coalfield||Realistic Design Of Ground Control Based On Geotechnical Dat||Underground High Resolution Seismic Method As A Low Cost Alt||Pillarless Longwall Mining For Multiple Seams||Stable Entry Design In A Multi-Seam Environment||Evaluating Roof Control In Underground Coal Mines With The C||Hazard Mapping Combining Geostatistical Modeling Of Coal Min||Stereological Sampling And Analysis For Characterizing Disco||Determining Horizontal Stress Direction Using The Stress Map||Stability And Stress Evaluation In Mines Using In-Seam Seism||Hydrogeologic Effects Of Subsidence At A Longwall Mine In Th||Monitoring Railroad Response To Mining Subsidence And Assess||Study On The High-Pressure Grouting Of The Overburden For Su|