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|This manuscript describes an extensive ground control study at the Inland Steel No. 2 Mine near McLeansboro, IL, conducted by the U.S. Department of the Interior's Bureau of Mines (USEM) in cooperation with Inland Steel Coal Co. The mine experiences severe ground control problem primarily due to high horizontal stress, particularly at entry intersections. Mine experience has shown that reorienting mine entries, modifying the bolting pattern, and altering the mining sequence are effective in reducing the severity of roof falls and out-of-seam dilution. However, the frequency of roof falls has not been significantly reduced. This research project was designed to provide a thorough explanation of the intersection failure mechanism through combined analyses of company in-mine experience and Bureau field measurements. Stresses and deformations were monitored in a four-way intersection during all stages of development and were related to site observations and theoretical analyses. The results of the combined analyses indicate that high horizontal stress is the predominant factor contributing to intersection roof falls in the Inland Steel No. 2 Mine. The horizontal stress induces shear zones to form along the outby 1 ribs, causing the immediate roof layer to detach 1 and behave as a cantilever beam oriented diagonally across the intersection and parallel to i the maximum horizontal principal stress. As the shear zone progresses upward, roof layers successively detach and fail, forming a dome-type roof fall.|
Additional chapters/articles from the SME-ICGCM book Proceeding of the Fifth Conference on Ground Control in Mining (ICGCM)
|Expanded Cement: New Solutions for Age-Old Problems||Determination of Effective Column Lengths for Resin-Grouted||How to Design an Efficient Roof Bolting Plan Based on Simple||Donut Cribbing--A Hew Heavy-Duty Roof Support Concept||Development of A Yielding Steel Post||Design Procedure for Arch Canopies for Rehabilitation of Hig||Investigation of Some Alternatives to Timber Posts and Cribs||Design and Field Testing of a Mobile Roof Support for Retrea||Change in Primary Roof Support System at Quarto Mining Compa||Remote Mining Using Water for Ground Support||New Type of Load Cell for Monitoring of Roof Bolt Tension||Field Measurements of Chain Pillar Response to Longwall Abut||Integrated Instrumentation Method of Stress State, Material||A Study of Roof Caving in the Eastern U.S. Coalfields||A Simple Tool to Measure Stress in Mine Backfill||Optimization of the Stress Control Method to Improve Product||Effect of High Horizontal Stress on Coal Mine Entry Intersec||Analysis of Small-Scale Thrust Faults and Their Effect on Co||A Case History of Computer-Aided Lineament Analysis for Grou||Designing for Upper Seam Stability in Multiple Seam Mining||Behavioral Aspects of Roof/Rib Injuries--Implications for Tr||Engineering Classification of Shales||Empirical Approach to Calculate Rock Loads in Coal Mine Road||Assessment of the Rockburst Proneness in Hard Rock Coal Mine||Outburst Control in Underground Coal Mines,||The Effect of Immediate Strata on Pillar Behavior in Retreat||Roof Control Problems on Development and Longwall Gateroads||A Case Study of Longwall Roof-Supports Interaction||Tailgate Support Evaluation at Plateau Mining Company||Methods of Controlling Hard Roof in a Longwall Face|