Summary
Indian coal measures have widely varying caving characteristics. The maximum roof span of a longwall or depillaring panel at the time of nether roof collapse is shown to have a direct relation withRQD from a study of 12 case histories. A similar relation between maximum unsupported span of openings and rock mass quality as defined by theQ-system was also demonstrated. A simple nomogram is presented to predict the face advance required to cause roof collapse when theRQD or rock mass quality is known.
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Sheorey, P.R. Use of rock classification to estimate roof caving span in oblong workings. International Journal of Mining Engineering 2, 133–140 (1984). https://doi.org/10.1007/BF00880878
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DOI: https://doi.org/10.1007/BF00880878