Estimation of support requirement for large diameter ventilation shaft at Chuquicamata Underground Mine in Chile

The Chuquicamata Underground Mine 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 copper ore. VP-CODELCO (Vice-President Projects Office of the National Copper Corporation of Chile) is currently developing a feasibility engineering evaluation of excavated infrastructure for the project. The evaluation considers, among others, the construction of two ventilation shafts of internal diameter 11 meters and approximate depth of 970 meters. A geo-mechanical study has been carried out to evaluate the stability of one of these shafts and to provide recommendations about support requirement. As part of this study, empirical methods, confinement-convergence analytical models, and two-dimensional and three-dimensional continuum models have been developed and applied to evaluate the influence of the stresses and existing geological features, such as the presence of two major shear zones and different lithological units, on the mechanical response of the excavation. This paper introduces general aspects of the Chuquicamata Underground Mine project and discusses in particular geo-mechanical analyses carried out to evaluate stability and support requirement for the large diameter ventilation shaft.