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|This paper presents the results of a case study conducted in a two-entry gateroad in a coal mine where excessive roof deformation and bolt loading resulted in failure of many roof supports. The instruments consisted of 16 fully grouted, strain gaged resin bolts, load cells on both full and partially grouted cable bolts, and vertical deflection multipoint extensometers. These instruments were installed on-cycle to measure loading on bolts in an existing support pattern and to determine if cable bolts could be used to improve roof stability. Results showed significant amounts of movement within the bolted zone. In sonic cases, these movements were enough to load the supports past their ultimate strength. Geology appeared to be a significant factor in localized roof degradation; that is, a very weak rock layer in the immediate roof overlain by a very strong rock layer contributed to the development of shear planes. Only one instrumented bolt had a maximum strain of less than 2,000 microstrain, which was the yield point of the steel. The average maximum strain on all bolts was 20.000 microstrain. However, electrical continuity to many gages was lost, and a pattern was noted that would indicate possible bolt failure. Wire mesh and concrete cans installed as secondary support performed very effectively.|
Additional chapters/articles from the SME-ICGCM book 17th International Conference on Ground Control in Mining (ICGCM)
|Gateroad Pillar Extraction Experience at Jim Walter Resource||Stability of Backfilled Cross-panel Entries During Longwall||Mining Through In-panel Entries and Full-face Recovery Room||Cutable and Variable Yield Cement Cribbing Successfully Supp||International Experience with Longwall Mining into Pre-drive||Analysis of Geologic and Geotechnical Conditions and Their E||Comparison of Ground Conditions and Ground Control Practices||Application of Microseismic Monitoring to Longwall Geomechan||Control of Hard-to-Collapse Massive Roofs in Longwall Faces||A Study of Periodic Weighting of Longwall Supports||Effects of Panel Mining Sequence and Retreat Direction on th||Controlling Roof Beam Failures From High Horizontal Stresses||Roof Control Under Conditions of Shallow Depth and High Hori||Assessment of Roadway and Yielding-pillar Performance During||Practical Stress Modeling for Mine Planning||The Design of Room and Pillar Mining Systems in the UK||Geotechnical Planning and Development of the BHP Minerals Sa||Coal Pillar Life Prediction in the Vaal Basin, South Africa||An Analytical Approach to Determine Stress Distribution in L||In Situ Strength Testing of Rocks with the Borehole Penetrom||Performance and Safety Considerations of Hydraulic Support S||A Decade of Mobile Roof Support Application in the United St||A Critical Study of Strata Behaviour During Extraction of Pi||Progression of Longwall Gateroad Support as Conditions Chang||Application of the Coal Mine Roof Rating, Derived from Drill||The Effects of Reduced Annulus in Roof Bolting Performance||Laboratory and In Situ Results of a Slip Nut Yielding Rock B||Field Monitoring of Rock Bolting Performance in Weak Roof St||A Case Study of Bolt Performance in a Two-entry Gateroad||Automated Temporary Roof Support Systems: An Update||Safety and Productivity Innovations in Mechanized Bolting||Factors Influencing Intersection Stability in U.S. Coal Mine||Analysis of the Effect of Rate of Extraction on Strain Devel||Analysis of Panel Stability for Post-Mining Slurry Injection||Development of Timedependent Surface Subsidence Over the Tot||Transversely Elasto-Plastic Analysis of Surface Subsidence A||Landslide Occurrence and Causation in Steep Slope Areas of A||Rock Bursting and Seismicity During Ramp Development, Lucky||Advances in Remote Sensing Techniques for Monitoring Rock Fa|