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Coal bumps are brittle, violent failures associated with high stresses and competent host strata. To study bump mechanisms, conditions in the vicinity of a deep longwall mining face in bump-prone strata were monitored using three discrete systems. First, a microseismic monintoring network recorded mining-induced seismic events throughout the mine and surrouning strata. Second, pressure variations and distributions on the longwall shield legs across the face were recorded. Last, tomography surveys imaged seismic transmission properties ahead of the face. Results from the three systems were correlated in an effort to increase understanding of mining-induced stress redistribution and bump potential. An initial, one-week study showed that the correlation between averaged tomogram values and seismically active areas had a coefficient of correlation (R) of 0.89. Further results of these studies demonstrate that the tomography system is capable of imaging heavy shield-leg loading and bump-prone conditions prior to them disrupting the face operations.
| Author(s): | Westman-EC, Heasley-KA, Swanson-PL, Peterson-S |
| Reference: | In: Elsworth D, Tinucci JP, Heasley KA, eds. Rock mechanics in the national interest, Proc 38th U.S. Rock Mechanics Symposium, Washington, DC, 2001 Jul; :319-326 |
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