A thesis submitted to the Faculty of Engineering, University of the Witwatersrand, in fulfilment of the
requirements of the degree of Doctor of Philosophy in Engineering / The thesis describes the determination of the steady state line for the Merriespruit gold and Bafokeng
platinum tailings by means of triaxial undrained compression tests. It shows that there are numerous steady
state lines for the above mentioned tailings products and thatthe location oftheirsteady state lines in void
ratio- mean confining effective stress space is influenced by the percentage fines (particles smaller than
0.075mm) present in the tailings, among other factors. As the percentage fines increases so the steady
state line for the particular material shifts downwards in void ratio- mean confining effective stress space.
The difficulty of defining a unique steady state line for a particular fines content tailings, due to errors in
measurement of initial size, mass, etc. and changes in void ratio due to flooding, saturation and
consolidation of the moist tamped triaxial test samples is illustrated and it is recommended that error bands
be assigned to the steady state lines.
The steady state lines determined for the Merriespruit gold tailings and the concepts of liquefaction are
combined with evidence obtained from the post failure investigation into the Merriespruit flow slide failure
to prove the premise that the flow slide was as a result of static liquefaction failure of the tailings. It is also
illustrated that the notion of using a single steady state line to evaluate the liquefaction susceptibility of a
tailings dam is insufficient due to the particle size distribution of the tailings varying along the beach length
of the tailings dam and the location of the steady state line being influenced by the percentage fines
content.
Flume modelling using the Merriespruit gold tailings were carried to obtain a qualitative understanding of
the behaviour of flow slides. Comparisons between the flume model tests and the Merriespruit flow slide
(prototype) showed that it is difficult to obtain a correlation between the two due to the influence of scale,
different dominating forces in the model and prototype and the inherent variability associated with such
geotechnical phenomena- particularly in the preparation and deposition of the tailings in the flume model.
Keywords: liquefaction, steady state line, flow slide, failure, flume modelling, Merriespruit, Bafokeng,
gold, platinum, tailings / AC 2018
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/23715 |
| Date | January 2004 |
| Creators | Papageorgiou, George |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
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