Page 464 - Rock Mechanics For Underground Mining

LONGWALL AND CAVING MINING METHODS

Figure 15.13 Plan view of micro-
seismic event locations 10–20 m
above the seam and relative to a fixed
face position, Gordonstone Mine,
Queensland, Australia (after Kelly
et al., 2002).

caving of the super-incumbent strata, leading to what is known as periodic weighting,
and often over-loading of the face supports. In extreme cases where large volumes
of rock hang up, sudden collapse of the strata into the mined-out void may produce
damaging air blasts. This problem has been alleviated in Australia by the innovative
use of real time micro-seismic monitoring to provide an indication of the onset of
large scale failure and possible wind blasts, and the hydraulic fracturing technique to
induce controlled caving (Hayes, 2000, Jeffrey and Mills, 2000).

shear of piezometer

Figure 15.14 Distribution of micro-
seismic events located within the
central third of a longwall panel
viewed from the side and relative to
a fixed face position, Gordonstone
Mine, Queensland, Australia (after
Kelly et al., 2002).
446