Slope design in challenging conditions at El Teniente, Chile

The El Teniente mine complex, owned and operated by the National Copper Corporation of Chile (CODELCO), is located about 80 km south of Santiago, Chile in the Andes Mountains, at 2,500 meters above sea level. The complex includes a series of underground operations that use block caving and panel caving to extract copper.

To provide flexibility in production rates and for strategic planning purposes, CODELCO is currently evaluating the Rajo Sur project at a pre-feasibility engineering level. This project involves developing and operating an open pit near the southern border of the subsidence crater. The close proximity to the subsidence crater makes Rajo Sur a challenging project, and a clear example of open-pit mining in difficult ground conditions.

To evaluate the mechanical stability of the open-pit walls, SRK studied approaches involving bench-berm design, and slope stability, at bench, inter-ramp and global scales, based on limit equilibrium models and finite difference elasto-plastic continuum models. SRK developed a complex three-dimensional mechanical model to assess the influence of subsidence cracks and abrupt topography on the stability of the planned open-pit walls, particularly in the southern boundary of the crater.

Since subsidence due to underground caving is a dynamic process, and the crater boundary location would have a pronounced effect on the stability of the planned pit walls, SRK has recommended studies which include different scenarios of underground development.

Esteban Hormazabal: ehormazabal@srk.cl

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