Geomechanical evaluation of caving macro-block options at Chuquicamata Underground Project in Chile using three-dimensional numerical modelling

The Chuquicamata Underground Project in the Atacama Desert in northern Chile is one of the largest planned mining projects in the world to use the method of block caving with macro-blocks option, to mine out copper ore. VCP-CODELCO (Vice-President Office of the National Copper Corporation of Chile) is currently completing a pre-feasibility engineering evaluation of this project, which considers the construction and operation of at least two macro-block mining units to be managed independently from each other. A geomechanical study has been carried out to evaluate various options related to pillar sizes and mining sequences for the macro-blocks caving configurations considered for the project. As part of this study, complex three-dimensional continuum models have been developed and applied to evaluate the influence of the above mentioned variables (and existing geological features such as the presence of a major fault and different lithological units) on the mechanical response of the underground openings —particularly, in regard to stress concentration developing in critical areas of the excavations such as macro-blocks pillars and rib-pillars. This paper describes general aspects of the Chuquicamata Underground Project, focalizing mainly on the three-dimensional geomechanical analysis carried out to evaluate the feasibility of the project.