M.Sc. (Geology) / The purpose of this work was to attempt to understand the behaviour of the ground around a series of holes bored in gold bearing rock by a reef boring machine. Furthermore this ground behaviour is compared with existing theoretical concepts of rock behaviour. The experimental boring site and the sequence of events at that site are described. The state of the rock surrounding the excavations is observed to deteriorate with increase in mining. The fracturing observed is characterised by spalling on the sides of the bored holes. This spalling increases in severity with closeness to the bored out region. Calculations of the stress acting on the sides of the bored holes were made from elastic theory using two techniques. One of these was a quick graphical technique and the other was a more complex analytical one. The analytical technique was used as a check on the results of the graphical technique. Finally the extent of spalling on the sides of the holes is compared with the theoretical stresses. A close correlation is found, and spalling appears to start when the stress level reaches the strength of the rock. As the stress level increases spalling increases in severity until such time as the ground around the bored area is fractured by large through going fractures. At this stage holes bored in this ground no longer spall.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:uj/uj:11298 |
| Date | 02 June 2014 |
| Creators | Adams, Graham Richard |
| Source Sets | South African National ETD Portal |
| Detected Language | English |
| Type | Thesis |
| Rights | University of Johannesburg |
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