Mapping stress changes with microseismics for ground control during longwall mining.
Proceedings: mechanics and mitigation of violent failure in coal and hard-rock mines. Maleki H, Wopat PF, Repsher RC, Tuchman RJ, eds. Washington, DC: U.S. Bureau of Mines, 1995 May; :91-103
Safe and efficient coal mining depends on the rapid identification of hazards that can develop ahead of a mechanized longwall face. The U.S. Bureau of Mines is committed to improving the ability of the mining industry to detect ground control hazards through novel technologies. One of these technologies utilizes microseismic monitoring and analysis to determine stress changes in a mine that might lead to hazardous conditions. This paper summarizes the results of field studies conducted over several years in four underground coal mines. Microseismic information was collected using geophone arrays situated in the gate road entries of the producing longwalls. Typically, signals were processed to determine source locations and intensities, which were then mapped in relation to longwall coordinates. Frequency and energy distributions of microseismic events were calculated in relation to spatial coordinates and were also determined relative to face position. These distributions show that activity changed with distance from the face, across the panel, and in the support pillars as mining progressed. The data were also compared to concurrent shield and pillar pressure monitoring results and demonstrate the potential of microseismic monitoring to indicate stress changes over a larger area than normally can be examined using conventional techniques.
Mining-industry; Coal-mining; Rock-falls; Rock-bursts; Rock-mechanics; Underground-mining; Control-technology; Geology; Geophysics; Engineering-controls; Computer-software; Ground-control; Ground-stability
Maleki-H; Wopat-PF; Repsher-RC; Tuchman-RJ
Proceedings: mechanics and mitigation of violent failure in coal and hard-rock mines