Abstract
This paper presents a probabilistic vulnerability analysis of two pit profiles within an active mine in Austral Africa. The profiles exhibit differing geological conditions, necessitating a nuanced assessment of their stability under varying operational and care scenarios. The study employs a prior published quantitative semi-empirical methodology to evaluate the evolution of annualized probability of failure (PoF) under different factors of safety (FoS) and levels of maintenance. The analysis encompasses four hypothetical scenarios representing varying degrees of care, maintenance, and dewatering activities for each profile. As expected, results indicate that maintenance practices, particularly dewatering, significantly influence slope stability, with neglect leading to elevated PoF levels. The study extends across multiple time horizons, from yearly assessments to long-term projections spanning 5, 10, 20, and 50 years.
Findings reveal that while increasing FoS generally reduces PoF, scenarios with reduced maintenance and FoS exhibit persistent vulnerabilities, especially over longer time frames. Profiles in more difficult geological conditions, demonstrate heightened vulnerability, underscoring the importance of tailored maintenance strategies. Comparisons with benchmark values derived from industry standards provide further insights into the effectiveness of current maintenance practices. This analysis reaffirms the significance of the current standard of care within the examined pit. Moreover, the proposed approach, complemented by Bayesian updates, holds promise for informing long-term and closure designs, facilitating risk-informed decision-making, and supporting efforts to achieve ALARP (As Low As Reasonably Practicable) conditions.
