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|One of the major difficulties in the proper characterization of rocks surrounding excavations is the lack of data. The existing method for strength determination requires core drilling for sample collection, which, when performed from the surface is costly, and when performed underground, in addition to its cost, interferes with the mine operations. I-landling samples tested in the laboratory is troublesome and also influences the obtained results. Over several years. the author has been interested in developing a method of in situ strength determination that could rapidly generate strength data at low cost without a negative effect on mining activities. The recently developed borehole penetrometer is an improved version of the initial design ( 3 inches in diameter), which was used mainly for strength determination of coal pillars. The new penetrometer has been designed to work in 1.5 inch diameter holes. Such holes can be drilled at low cost with either hand held drilling machines or roof bolters. eliminating limitations of the previous system and opening the possibility of broad application. Strength testing of roof rock around longwall pillars is an example of an obvious benefit when designing secondary roof support. In the paper are given the principles of work of the apparatus and examples of the obtained strength data.|
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|