Evaluation of strata conditions and performance of support systems of the Emerald Shaft Gold Mine in Gauteng Province of South Africa

Abstract

The creation of underground excavations causes disturbances in the rock mass, leading to geotechnical uncertainty and increased risk of fall of ground or backbreak. The incompetency of the rock mass, high tensile fractures, and concentration of horizontal virgin and mining-induced stresses pose significant threats to both safety and production, highlighting the need for effective strata control measures. This study aimed to evaluate the strata conditions and performance of support systems of the Emerald Shaft Gold Mine to ensure long-term stability. The objectives of the study included reviewing the mine design and layout, determining geological conditions and their influence on the rock strata, examining the performance of the support systems used in the raise and production stopes of the Emerald Shaft Gold Mine., and recommending appropriate strategies for strata control. A comprehensive geotechnical investigation was conducted at the Emerald Shaft Gold Mine to characterize the rock mass and inform mine design. The study applied a multi-disciplinary approach including field profiling, geological and geotechnical mapping, field test and laboratory analysis, field observations, and analytical and numerical modelling. The investigation involved a detailed analysis of rock mechanic data, geological conditions, and raise and stope support systems to evaluate the stability of the mine. The study revealed complex geological conditions, variable rock competency, and distinct mechanical properties. The rock mass quality was compromised by regional geological features, such as dykes and faults. The findings highlighted the importance of site-specific characterization, comprehensive support design, and targeted support measures to ensure safe and efficient mining operations. The study also identified areas prone to rockfalls, fall of ground incidents, and stope instability, emphasizing the need for robust support design and regular monitoring. The study concluded that a tailored support design approach, considering tendon performance, ground conditions, and stress loading, is essential to ensure optimal ground stability and prevent rockfalls. The recommended support measures include the installation of grouted dowels, pre-stressed elongates, and fibre-reinforced shotcrete. Regular monitoring and maintenance of support systems are crucial to ensure their effectiveness and prevent accidents. The study's findings and recommendations provide valuable insights for mine design, support strategies, and safety protocols at the Emerald Shaft Gold Mine, and can be applied to similar mining operations. This study contributed significantly to the understanding of strata conditions and support systems in Emerald Shaft Gold Mine. The research provided new insights into the complex geological conditions and variable rock competency of the mine, highlighting the importance of site-specific characterization and tailored support design. The findings of the study and recommendations offered valuable contributions to the existing knowledge on strata control and support systems, providing a framework for improving mine safety and efficiency. Specifically, this research demonstrated the effectiveness of a multi-disciplinary approach in evaluating rock mass quality and designing optimal support systems and highlighted the need for regular monitoring and maintenance to ensure the effectiveness of support measures.