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|In general, the direction of the maximum horizontal stress in the eastern United States is fairly well defined. However, the variation of the magnitudes of the horizontal stresses is not very well understood. Because the horizontal stresses cause severe ground control problems in underground coal and limestone mines throughout the eastern United States a more complete understanding of how the magnitudes vary would be useful for developing mine design strategies to combat horizontal stress related ground control problems. Therefore, in this National Institute for Occupational Safety and Health (NIOSH) study, the variation of the magnitude of the horizon stresses in sedimentary deposits in the eastern and Midwestern United States are examined with respect to two factors, the elastic modulus of the rock and the site depth. Stress measurements from thirty-seven sites are used in the evaluation. Examining the applied excess strains indicates that the eastern United States can be, separated into high and low strain zones. For most of the eastern United States the maximum applied excess or tectonic strain ranges from only 300 to 550 micro strains. However, there is one area, a portion of the Beckley seam in the central Appalachian region where the strains are significantly higher than the other regions. In this higher strain zone, the maximum applied tectonic strains range from 700 to 1,000 micro strains. Regression models for each zone based on the elastic modulus can explain between 83 to 85% of the variation of the maximum horizontal stress. Because one region, the northern Appalachian district, has strains that are about 20% higher than the other regions in the low strain zone, multiple strain models based on geographic regions were developed for the low strain zone that can explain 87 to 91% of the maximum horizontal stress variation with the elastic modulus. Depth was found not to be a significant causal factor in any increase in the horizontal stress even though the site depths ranged from 275 to 2,500 ft. Beyond a theoretical increase, based on Poisson's effect and gravity, no other increase in the horizontal stress with depth can be justified with this data. The most significant factor controlling the variation of the maximum horizontal stress is the elastic modulus of the rock, not the overburden depth.|
Additional chapters/articles from the SME-ICGCM book 22nd International Conference on Ground Control in Mining (ICGCM) 22nd
|Pillar Design and Roof Support for Controlling Longwall Head||Stress Analysis and Support Design for Longwall Mine-Through||The Utilisation of Numerical Modelling to Predict Water and||Longwall Roof Fall Prediction and Shield Support Recommendat||Comparison Of Multiple And Single Entry Roadways For Highly||Numerical Modeling Of Longwalls In Deep Coal Mines||The Characteristics Of Mining-Induced Fractures In Overlying||Design And Experience Of Total Extraction Room And Pillar Op||Using Site Case Histories Of Multiple Seam Coal Mining To Ad||Mining Method For Extracting An Eight Metre Coal Horizon Con||Stooping Low Safety Factor Pillars At Goedehoop Colliery||Modelling Of Pillar Stability In Room And Pillar Mines||Pillar Optimization For Initial Design And Retreat Recovery||Application Of RMT's Remote Reading Telltale System To||Rock Mechanics Study Of Lateral Destressing For The Advance-||New Tools For Roof Support Evaluation And Design||Considerations For Using Roof Monitors In Underground Limest||Mine Roof Geology Information System (MRGIS)||Imaging Ahead Of Mining With Radio Imaging Method (RIM-IV) I||Geophysics For The Detection Of Abandoned Mine Workings||Investigation Of Seam Thickness And Seam Splitting Within A||Determination Of Rock Strength Properties Using Geophysical||RQD from the Barrel to the Box: Weatherability May be a Bett||A probabilistic approach to ground support design in undergr||The Requirements of a Database to Store Geotechnical Data to||Variation of Horizontal Stresses and Strains in Mines in Bed||Geotechnical Planning Basis for the Optimization of Workings||Tensile roof failure arising from horizontal compressive str||Study of load transfer capacity of bolts using short encapsu||Intersection Stability and Tensioned Bolting||Premature Rock Bolt Failure Through Stress Corrosion Crackin||Short-encapsulation Pull Tests for Roof Bolt Evaluation at a||Field Test with Strain-gauged Friction Bolts at the Gold Hun||Directional Rock Bolt Pullout Tests as Index Tests for Estim||Eclipse Bolting System||The Application of Pre-tensioned Grouted Tendons at Harworth||Investigation into the Extent and Mechanisms of Gloving and||Developments in Improving the Standard of Installation and B||Development of Geotechnical Procedures for the Analysis of M||Recent Developments in the Use of Seismic Tomography in Long||Pumpable Roof Supports: Developing Design Criteria by Measur||Design Considerations of the Secondary Roof Support for Long||The Effect of Standing Support Stiffness on Primary and Seco||Numerical Modeling of the U1A Complex at the Nevada Test Sit||Rock Mechanics and the Analysis of Underground Mine Stabilit||A Study of Potential Fault Reactivation and Water Intrusion||The Elimination of Rock-fall Fatalities in Ontario Hardrock||Root Causes of Groundfall Related Incidents in U.S. Mining I||Analysis on the Dynamics of Mining Subsidence in Range of a||Mitigating Subsidence Influences on Residential Structures C||Influences of Longwall Subsidence on a Guyed Steel Tower - A||Surface Movement of Super-wide Longwall Panels Using Top-coa||New Approach to Evaluate the Stability of Yield Pillars||Experimental Study of Acoustic Emission Characteristics for|