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|The stress-field orientation mapping and analysis (SOMA) technique for determining the operative stress field near mine workings and its relationship to various fracture sets is described using Dickenson-Russell Coal Company's Laurel Mountain mine as an example. Carried to its practical application, this technique ultimately defines the optimal orientation for the mine workings wherein pillars, rather than rock bolts or other roof support methods, dominantly shoulder support of the highest-probability, potential, roof-fall blocks. It also provides a predictive tool describing local variability in rock deformation and in secondary roof support methods. Fracture discontinuities within a rock mass, either as pre¬existing natural fractures or as mining-induced fractures, are uniquely necessary for every brittle-deformation ground failure including roof falls. Prediction and mitigation of roof falls requires quantifying the interaction between the fracture sets and the operative principal-compressive¬ stress-axis orientation (olo). The SOMA technique utilizes the interaction between fractures and 61o, specifically their dilation or closure, to calculate the orientation of 610, and to estimate the orientations of 62o and o3o. A stereonet program is used to organize and statistically analyze the fracture data, and then to determine the optimal orientation for the mine workings. The final step in the SOMA technique involves modeling the Laurel Mountain mine using a 2-D, finite-element, modeling program. This assures that the interpretations regarding the optimal working orientation closely match the deformation features observed in the mine. It also provides a predictive tool describing highly variable stress and strain partitioning, seemingly erratic rock-bolt failures and the interactions between different sets of mine workings within different coal seams. The critical importance of including the fracture sets is well illustrated in the Laurel Mountain mine where the effects of earlier mining of an underlying seam is contrasted in both a fractured and otherwise identical non-fractured model to illustrate the consequences of ignoring fractures in a predictive roof-fall model.|
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|