Page 50 - University of Pretoria RESEARCH REVIEW 2018

Rock engineering research
makes underground mining safer
Francois Malan, Department of Mining Engineering
Innovative methods of layout design and improvements to the support of deep tabular stopes are required to exploit South Africa’s vast remaining gold resource.
stability of the fracture zone near the edges of tabular excavation layouts when different mining rates and
face advance increment lengths are scheduled. The model specifically accommodates energy dissipation computations in the developing fracture zone near the edges of these excavations. This allows the released energy to be used as a surrogate measure of ongoing seismic activity and addresses a number of the weaknesses in the traditional usage of released energy as a criterion for the design of seismically active layouts.
The effectiveness of stope support in deep gold mines was also assessed. The design of rockburst-resistant support for shallow-dipping tabular excavations is particularly problematic when the stoping width is very small. The need for area support to give improved protection to stope workers was highlighted in the research.
The work resulted in a number of publications in 2018, of which two were published in the prestigious International Journal of Rock Mechanics and Mining Science.
John Napier, Extraordinary Professor in the Department of Mining Engineering, is a key collaborator
in this research programme. Collaboration with the rock engineering groups of Northam Platinum, Impala Platinum, Lonmin Platinum and Harmony Gold were also established in 2018.
The gold mines of South Africa are the deepest in the world and more than 50 000 tons of gold have been extracted since 1886. Even after a sustained production period of mining over this period, the Witwatersrand Basin is still the world’s largest resource of gold.
Recent rockburst accidents have drawn attention to the need for research into methods to mitigate the risks associated with mine seismicity, and for the development of updated design criteria for the very deep mines. Remnants and pillars (small, isolated blocks of reef) are mined in many of the older operations. There is currently a great need to improve the criteria
used to select which remnants can be mined safely. Work also needs to be done to improve the support design methodology for rockburst conditions.
In 2018, Professor Francois Malan extended the rock engineering research programme in the Department of Mining Engineering to focus on improved methods for layout design and the support of tabular hard rock stopes. This work has also formed part of the Harmony Chair in Rock Engineering.
A key breakthrough by the research team was the development of a numerical modelling method to determine the time-dependent
Stope supports in a South African gold mine.
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