An independent review and summary of geotechnical information pertaining to the sidewall stability of the Kimberley "Big Hole" mine, with specific focus on the weathering and deterioration of the Kimberley shales.
Thesis (MEng)--Stellenbosch University, 2017.
The Kimberley “Big Hole” Mine in the center of Kimberley experiences frequent small scale toppling and landslide slope failure events, which causes the sidewalls of the pit to slowly migrate outward towards surrounding businesses and infrastructure. The reason for slope stability problems and slope failures can be ascribed to the vast susceptibility of the underlying Kimberley shales to weather and deteriorate when exposed to the atmosphere and natural weathering conditions. This sets into motion a process known locally as “mine pit break-back”, where regression of the underlying shale unit causes the overlying dolerite cap to break off into large dolerite blocks or boulders, which eventually topples over and into the open mine pit as single block toppling slope failure events. In order to help combat this problem of undermining at the Kimberley “Big Hole” Mine, five different dust and erosion control liquids were identified on the basis of forming a waterproof and weather resistant base around the surface it is applied to. In theory, all five dust and erosion control liquids should prevent water ingress through the surface of the rock and create a protective layer that will increase rock durability and weathering resistance of the Kimberley shales. These products were tested by using various durability and weathering test techniques including absorption tests, cyclic wetting and drying tests, comparative accelerated weathering tests and slake-durability index tests. The ultimate aim of this project was to identify one of these dust and erosion control liquids as a viable solution towards the defined slope stability problem at the Kimberley “Big Hole” Mine and in turn stop the process of mine pit break-back by applying this product to the sidewalls of the pit. In addition, many non-conventional techniques of measuring ground movement or displacement around large open pits, such as the Kimberley “Big Hole” Mine for example, were used to identify the entire extent of slope stability problems at the Big Hole Mine, as well as determine the migration pattern for the sidewalls over the past 46 years. These ground movement measuring techniques included a direct visual inspection of the slopes and sidewalls of the Kimberley “Big Hole” Mine as well as the remote sensing and pixel tracking of aerial photographs between the years 1968 and 2014. The abovementioned procedures delivered significant result towards combatting the defined slope stability problem at the Kimberley “Big Hole” Mine and conclusions and recommendations surrounding further work at the open pit mine is worth further investigation. The Sasbind DECL product prevailed as the most successful and effective DECL product with regards to increasing the rock durability and weathering resistance of the Kimberley shales after each durability and weathering test, which lead to the conclusion that application of this product to the sidewalls of the Kimberley “Big Hole” Mine could prove to be highly successful in addressing the slope instability problem at the Big Hole Mine. Further testing in this regard is justified and recommended.
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