Geotechnical Risk Analysis For The Closure Alternatives Of The Chuquicamata Open Pit

L‐F Contreras, E Hormazabal, R Ledezma, M Arellano
Tuesday, April 9, 2019
First presented: 
First International Conference on Mining Geomechanical Risk 2019
Published paper
The development of the geotechnical risk model for the Chuquicamata mine started in 2005 and included the safety and economic impacts of slope failures at different scales (Tapia et al. 2007; Steffen et al. 2008). The model has been updated recently to include a quantitative evaluation of large economic impacts derived from inter‐ramp and overall slope failures using a probabilistic approach (Contreras 2015). This paper describes how the later component of the model was used as a tool for the evaluation of four closure alternatives for the open pit. The methodology included three main tasks:
  1. Evaluation of the Probability of Failure (PF) representative of the stability conditions of pit slopes.
  2. Evaluation of the consequences of slope failure associated with economic losses derived from impacts on production and costs.
  3. Generation of risk maps to compare several closure alternatives.
The results of these analyses provided information on magnitude of impacts and their likelihood for the four closure alternatives evaluated. The evaluation of these results facilitated the selection of the appropriate closure alternative considering the mine reference criteria for economic risk.

About the Authors

Luis Fernando Contreras, PEng, MSc,
Luis Fernando Contreras has been involved in the field of Geotechnical Engineering for the past 35 years. His expertise includes: risk evaluation studies for mine design and project optimization; pit slope engineering and geotechnical design for open pit mining; tunnel engineering and geotechnical design of underground excavations for civil engineering projects; dam engineering and geotechnical design of rock fill and earth fill dams; foundation engineering, numerical modelling, instrumentation design, rock mechanics analysis; geotechnical studies for hydroelectric developments, open pit mining and transport projects, including site investigations, detail design, preparation of bidding documents and specialized advisory during construction.
Esteban Hormazabal, PEng, MSc,
Esteban is a Civil Mining Engineer and holds a Master of Science (Geophysics) specialized in applied hydrogeology. He has 24 years of specific experience in geotechnical engineering, rock mechanics and geotechnical instrumentation, having worked in different mining and civil engineering projects. 
Additionally, he is an expert in analysis and geomechanical design of underground mining and surface excavations using 2D and 3D numerical modelling, stability analysis and slope design in open pits and waste dumps. 
He has led different and important open pit and underground mining projects in Argentina, Brazil, Chile, Colombia, Kazakhstan, Mexico, Peru, Russia, Uruguay and USA. 
Esteban has authored several publications and has been speaker at different national and international conferences. He is a Competent Person of AusIMM and the Commission for the Qualification of Competencies in Mineral Resources & Reserves of Chile (QP). He has been professor of  the Rock Mechanics Chair at the Universidad Católica de Chile from 2013-2018.




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