Geotechnical risk management for Victor Mine closure

Desjardins, Mathieu; Graaf, Phil de; Beale, Geoff; Rougier, Marc

doi:10.36487/acg_repo/2025_22

Cited by 3 publications

(1 citation statement)

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“…However, the increase of the water body inside the open-pit also acts as a supporting force, and the pit lake's creation has been reported to improve slope stability (e.g. Desjardins et al 2020;Faur et al 2020).…”

Section: Introductionmentioning

confidence: 99%

The Evolution of Geotech - 25 Years of Innovation

Hammah¹,

Yacoub²,

McQuillan³

et al. 2021

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I have been teaching and researching rock engineering and practicing as a consultant since 1972. I have spent most of that time in underground mining. I have seen significant changes, both evolutionary and radical, in the sector. In this paper, I reflect on some of these changes in mining geomechanical practice. I will also comment on some of the positive and occasionally less positive impacts of these changes. One constant throughout my career is that geomechanical designs will always be fraught with uncertainty. As a result, we will discuss geomechanical design as being, in its essence, a risk management exercise. I will argue that, as impressive as modern numerical analysis techniques are, they do not on their own mitigate design risk; under worst-case scenarios, they make things worse. Empirical and simple models must be used as a check. The paper intends to provoke healthy skepticism in geomechanics practitioners, designers and managers regarding all the aspects of the geomechanical analysis and design process. A failure to recognize the risks in these processes can have catastrophic effects.

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Section: Introductionmentioning

confidence: 99%

The Evolution of Geotech - 25 Years of Innovation

Hammah¹,

Yacoub²,

McQuillan³

et al. 2021

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Geotechnical Issues in Decommissioning Surface Lignite Mines—The Case of Amyntaion Mine in Greece

Kavvadas

Roumpos

Servou

et al. 2022

Mining

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Recent changes in the fossil-fuel energy sector require coal mining industries to plan for the future, including developing procedures for decommissioning and closure associated with mines. In surface coal mining, the geotechnical issues of decommissioning include the long-term stability of the pit slopes, particularly as the pit is gradually filled with water. This paper investigates such slope stability issues, with emphasis on the conditions prevailing in the Amyntaion surface lignite mine, in Western Macedonia, Greece. Analytical and numerical methods have been developed and used to estimate the temporal evolution of the overall safety factor, as the water level in the pit rises, creating a lake. It is shown that until the water level in the lake reaches a critical depth of approximately 15–35% of the final equilibrium condition, the safety factor against the overall slope instability decreases slightly (by about 3% in the case study, and up to 5–10% in other conditions) compared to its value at the end of exploitation. At higher lake levels, the safety factor increases significantly, as the beneficial effect of the lake water pressure acting on the slope overcomes the adverse effect of pore water pressure rise inside the slope. In typical mines, the critical water depth is achieved within a few years, since the surface area of the pit is smaller at deeper levels; thus, more favorable slope stability conditions are usually reinstated a few years after mine closure, while the small reduction in safety during the initial stages after closure is inconsequential. The paper investigates the parameters influencing the magnitude of the small reduction in the short-term safety factor and produces normalized graphs of the evolution of the safety factor as the lake water level rises. The results of the analyses can be used in preliminary closure studies of surface coal mines.

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Stability of open pit lignite excavations during flooding: comparison of a simplified analytical tool with limit equilibrium computational analysis

Kontopidis,

Theocharis,

Koukouzas

et al. 2022

Górnictwo Odkrywkowe

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A common practice for valorizing abandoned open-pit mines is flooding them to form pit lakes. Slope stability in post-coal areas is critical due to failure incidents reported in surface coal mines during operation and valorization. An analytical model was recently presented concerning evaluating the pit lake’s slope stability in the presence of a weak zone. The present work compares that analytical model with a limit equilibrium computational approach for lignite mines’ stability. Assumptions of each model are discussed, and identical geometries and geotechnical parameters are implemented. It is concluded that the Safety Factor and its evolution are very sensitive to the water regime and the lake’s depth for the analytical model. On the other hand, the limit equilibrium analysis considering the same piezometric and lake levels proposes a drastically different SF evolution. Overall, the differences between the analytical and the limit equilibrium analysis might refer to different water conditions in practice and should be implemented with due caution.

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Geotechnical risk management for Victor Mine closure

Cited by 3 publications

References 0 publications

The Evolution of Geotech - 25 Years of Innovation

The Evolution of Geotech - 25 Years of Innovation

Geotechnical Issues in Decommissioning Surface Lignite Mines—The Case of Amyntaion Mine in Greece

Stability of open pit lignite excavations during flooding: comparison of a simplified analytical tool with limit equilibrium computational analysis

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