Design of stable inter-pillar spans at Tao Lekoa Mine
Date
2008-06-27T10:12:42Z
Authors
Dunn, Michael John
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Abstract
Since the commencement of mining at Tau Lekoa Mine in 1991, large
geologically controlled falls of ground (FOG) have been problematic. Crush
pillars are used to control these instabilities. Limiting of panel spans and cutting
of pillars results in practical problems and production constraints which influence
labour efficiencies, productivity and ultimately the economics of mining.
This study analysed 81 large FOG that occurred over 1991 to 2001 using
statistical methods. Statistical distributions describing the falls of ground, rock
mass properties and mining parameters were determined. A probabilistic
approach was used to evaluate stable spans and the crush pillar stability.
The probability of large hanging wall instabilities was assessed for several
mining situations using a Fault Tree methodology.
Larger spans are possible provided an appropriate internal support system is
designed. A probabilistic or risk based design approach is recommended as this is
considered more logical than a deterministic approach.