Abstract
M.Sc. (Geology)
Analyses show that the effect of inter-panel lag on hanging wall instability
is an important factor affecting rock-fall accidents and production losses
in gold mines utilising segmented longwall mining methods.
The study emphasises the effect of inter-panel lag on the development of
mining-induced fractures which are considered a major contributor to
hangingwall instability in geologically undisturbed ground.
The geology and mining geometry at Western Deep Levels, Limited,
particularly at the selected research site, is outlined. The data
collection, which is facilitated by the use of stereo-photogrammetry
and computer-aided data handling, is described.
Three types of mining-induced fracture are evident. The effects of
inter-panel lag and geological inhomogeneity on the orientation and
density of the mining-induced fractures are illustrated and discussed.
The effects of inter-panel lag length on energy release rate are
demonstrated and discussed. Microseismic event location data analyses
are used to elucidate the fracturing process that takes place in the
rock ahead of the mine face.
Practical suggestions regarding the reduction in number and length of
inter-panel lags are made, in the light of recent developments in the
field of rock-burst control.