Student Number : 7439270 -
MSc research report -
School of Mining -
Faculty of Engineering and the Built Environment / In tabular mining, common in South African gold and platinum mines, the removal of
the tabular ore body by mining operations leaves behind excavations known as
stopes. These stopes form the production areas of a mine and have to be supported in
order that a safe working environment is created. Stopes generally have widths of
close to a metre but, in some areas and on certain reefs, may be much wider. Prior to
the 1980s, a combination of in-stope pillars and timber was used to support these
stopes, but innovations from the 1970s have produced grout packs as a viable support
option. These packs are cast in situ through the use of cemented classified tailings
gravitated from surface and placed in reinforced geotextile bags at the stope face. As
these packs cure and become rigid they are able to bear load when compressed by
stope closure. In this way, the packs keep the working areas open.
To quantify the load-bearing capacity of grout packs, a range of sizes and designs was
tested in a laboratory press and, thereafter, a select few were tested underground.
Initially, two aspects of grout packs that had not been adequately quantified previously
were addressed. These were: the in situ load / compression characteristics of different
forms of grout packs; and the relationship between laboratory test results and in situ
performance. The laboratory test programme was extended to allow for an
investigation into methods of improving the yieldability of grout packs and the
possibility of using them to replace in-stope pillars.
It was found that the factors that most affect the initial strength and post-failure
characteristics of a grout pack are: the grout strength; the amount and type of steel
reinforcement; the inclusion of ancillary columnar support; and the height and diameter
of the pack. It was also found that grout packs could be used to replace in-stope
pillars, but that pack strength and spacing should be conservatively calculated before
implementation.
A provisional relationship between the behaviour of packs tested in a press and those
placed underground was determined.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/2138 |
| Date | 26 February 2007 |
| Creators | Grave, Douglas Marcus Hadley |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 2123931 bytes, application/pdf, application/pdf |
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