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|Pillar collapses have been studied for several years and can be classified into two types: nonviolent squeeze or violent pillar collapse, i.e., controlled or uncontrolled pillar collapse. Underground coal mines in Brazil are considered shallow mines, because the overburden thickness varies between 20 and 400 meters. For this reason, the coal pillars should be designed as permanent pillars to avoid subsidence and groundwater problems. In the last two years, various pillar collapses occurred, one being a violent collapse and the others being squeeze collapses. All these collapses were considered massive pillar collapses because many pillars were involved. In the violent pillar collapse case, the width¬to-height (w/h) ratio was less than three; although, the pillar safety factor (SF) was more than 1.3. There was a collapse of about 100 pillars in less than three hours. The objective of this study is to determine the mechanism of pillar collapse for this violent pillar collapse. Convergence monitoring and numerical modeling were applied to combine field data and theory to simulate the pillar collapse. Convergence field measurements introduce the arc-effect behavior for the roof. The results showed that other factors besides pillar geometry caused the pillar failure. Other parameters, mainly dip of the coal seam and presence of fractures and faults may affect the strength and failure mechanism of a pillar.|
Additional chapters/articles from the SME-ICGCM book 23rd International Conference on Ground Control in Mining (ICGCM) 23rd
|Geomechanical Criteria of Longwall Face Support Selection at||Rock Fracture, Caving and Interaction of Face Supports Under||Effect of the Approaching Longwall Faces on Barrier and Entr||Computer Simulation of Ground Behaviour and Rock Bolt Intera||lnterpanel Barriers for Deep Western U.S. Longwall Mining||Application of Yieldable and Cuttable Pump Crib in Longwall||Field Testing of a Real Time Roof Mapping Drilling Display S||Problems in "Void" Detection in Coal Mine Water Hazards||Violent Coal Pillar Collapse -A Case Study||Stooping Low Safety Factor Pillars at Goedehoop Colliery - 1||Laboratory Strength Testing of Coal from Selected Illinois S||Downhole Overcoring Stress Measurement at a Western Undergro||Effect of In Situ Stresses on the Stability of Coal Mine Dev||SOMA: A New Method to Calculate the Operative Stress Field:||Numerical Modeling for Increased Understanding of the Behavi||Evaluation of Rockburst Hazard from Core Testing||Investigation of Electromagnetic Emissions in a Deep Undergr||Development and Application of Geotechnical and Rockmechanic||Laboratory Testing of Rib Straps||The New Two-Dimension LaModel Program||Risk Assessment: Multiseam - Single Seam Mining||A Method To Determine Expander Spacing For Steel Pipelines I||A Case Study Of Abandoned Mine Subsidence At Dominion, Nova||Spatial Trends In Rock Strength - Can They Be Determined Fro||Development And Demonstration Of An Alternate Mining Geometr||Evaluation Of Polyurethane Injection For Beltway Roof Stabil||Application Of Ground Penetrating Radar To Evaluate The Exte||A Risk Assessment Tool For Open Cast Mining In South Africa||Analysis Of Practical Ground Control Issues In Highwall Mini||Preventing Falls Of Ground In Coal Mines With Exceptionally||Geo-Mechanical Property And Failures Of Weak Roof Shales In||Eclipse System Bolting In The Illinois Basin||Variation In The Load Transfer Of Fully Encapsulated Rockbol||Bolt Load Changes During Initial Face Advance And Cross-Cut||Coal Mine Primary Support Selection: Tension Versus Non Tens||Improving Stope Support At Modikwa Platinum Mine||3D FEM Simulation For Fully Grouted Bolts||An Investigation Into The Effectiveness Of Support Systems C||Hydraulic Prestressing Units: An Innovation In Roof Support||Improving Roof Truss Performance||Coal Combustion Byproducts-Based Artificial Mine Supports -||The Influence Of Horizontal Stress On Pillar Design And Mine||Investigation Of Pillar-Roof Contact Failure In Northern App||Mapping Hazards With Microseismic Technology To Anticipate R||Practical Detection Of Underground Mine Roof Failure||Heat-Imaging Experimental Study Of Reducing Local Gas Accumu||Microcirculation Theory Analysis Of Spontaneous Combustion O|