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|The United States Steel Mining Company, Inc., (USM) Lynch District, operated the No. 37 Mine in the Harlan coal seam, Harlan County, Kentucky, from 19'2 until its sale to Arch of Kentucky in 1984. Overburden depth varied from 400 to 2000 feet and mining height varied from 8 to 12 feet. In 1981, because of deep overburden, high seam height, and previous pillar stability problems, U. S. Steel Research and the Lynch Mining District entered into a joint project to measure longwall pillar stress. Eight gateroad pillars were instrumented with a total of 86 vibrating-wire stressmeters under overburden depths varying from 500 to 1550 feet. Stress-increase measurements were taken during: (1) pillar development, (2) retreat of longwall panel No. 1, and (3) retreat of longwall panel No. 2. Total average pillar stress was approximately three times the pre-mining stress with total stress at an individual meter reading 5.5 times the pre-mining stress. When maximum, measured average pillar stress was compared to pillar strength predicted by several popular pillar design methods, the pillars were found to be stronger than predicted. This paper will summarize the pillar instrumentation program and present the results. Stress distributions, average measured pillar stress, and comparison of measured pillar stress to predicted pillar strength by several design methods will be given.|
Additional chapters/articles from the SME-ICGCM book Proceeding of the Fourth Conference on Ground Control in Mining (ICGCM)
|Truss Bolting On-Cycle in Jane Mine Lower Freeport Seam||Design Of A Roof Truss Bolting Plan For Bear Mine||Tension-Torque Relationship For Mechanical Anchored Roof Bol||A Novel System For Automatic Installation Of Cement Grouted||Load Transfer Mechanics In Fully-Grouted Roof Bolts||An Investigation Of Longwall Pillar Stress History||Impact Of Horizontal Load On Shield Supports||Interaction Between Roof And Support On Longwall Faces With||Roof Control With Polyurethane For Recovery Of Kitt Energy?s||First Caving And Its Effects--A Case Study||Staubbekampfung An Schildausbau In Bruchbaustreben (Combatin||Yield Pillar Applications--Impact On Strata Control And Coal||Constraint Is The Prime Variable In Pillar Strength||Massive Pillar Failure--Two Case Studies||Investigations Of Underground Coal Mine Bursts||Destressing Practice In Rockburst-Prone Ground||Statistical Characterization Of Coal-Mine Roof Failure: Sugg||Pillar Design - Continuous Miner Butt Section And Longwall D||Design Factors In Near-Seam Interaction||Remote Sensing For Roof Control And Mine Planning: An Overvi||Design, Construction And Performance Of A Single Pass Lining||Computer Modelling And In Situ Instrumentation Techniques: A||A Sonic Wave Attenuation Technique For Monitoring Of Stress||The Radio Imaging Method (RIM) -- A Means Of Detecting And I||Clay Veins: Their Physical Characteristics. Prediction, and||Evaluation of the Point Load Strength for Soft Rock Classifi||Ground Control Experiences in a High Horizontal Stress Field||Horizontal Stresses and Their Impact on Roof Stability at th||Ground Control Problem Associated with Longwall Mining of De||Geotechnical Aspects of Subsidence over Room and Pillar Mine||Proposed Criteria for Assessing Subsidence Damage to Surface||Surface Subsidence. in Longwall Mining--A Case Stud||An Integrated Approach to the Monitoring and Modeling of Gro|