Slope Design at Cuajone Pit, Peru

Esteban Hormazabal, Gabriel Zuñiga and Felipe Gonzalez
Wednesday, September 25, 2013
First presented: 
Slope Stability 2013 Proceedings, September 25-27, 2013 Brisbane, Australia
Published paper
Rock Mechanics

The Cuajone porphyry copper deposit is located on the western slopes of Cordillera Occidental, the southern Andes of Peru. The current pit measures about 2.5 km east–west, 3.0 km north–south, and at the end of 2012, had a maximum depth of 950 m. Mining by open pit methods commenced in 1976 and has continued since that time. Ore production is 80 ktpd.

As part of the slope design program and slope optimisation, the past and present performance of the pit slopes was evaluated to provide information on the potential behaviour of future pit expansion. A geomechanical assessment is being carried out to evaluate the stability of the walls of the next expansion. To evaluate the stability of the open pit, a series of geotechnical studies have been performed. These studies involve, among others, slope stability analyses based on limit equilibrium methods and finite element numerical models. In addition, a detailed back‐analysis of a five million ton failure (DSE42) was performed to calibrate rock mass properties and to understand slope behaviour in poor rock mass quality.

This paper describes the back‐analysis of the DSE42 failure and the slope design process for the current pit and next pushback.

Feature Author

Esteban Hormazabal
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.


Head of Rock Mechanics Services
Min Eng, MSc (Geophysics), FAusIMM, SAIMM, CRIRSCO
SRK Santiago
SRK Latin America