Geotechnical challenges during excavation of Crusher Chamber 1, Andes Norte project, El Teniente mine R Valdivia Codelco, Chile R Padilla Codelco, Chile W Rodríguez Codelco, Chile P Landeros Córdova Codelco, Chile A Muñoz Codelco, Chile E Rojas Codelco, Chile Abstract The Andes Norte project is an expansion of the El Teniente mine and is planned to be the deepest project to enter production beneath the Esmeralda and Pilar Norte operating sectors. The material handling system involves transferring material from the productive sector via ore passes and loops with trucks, which move to a crusher inside the mine. Finally, the material is connected to a 9 km-long conveyor belt tunnel to the surface. The Andes Norte project Crusher Chamber 1 is the deepest cavern at the El Teniente mine, located 250 m below the current operative chambers. It is also the largest, with a total design volume of 74,000 m 3 . The entire design is a complex of several caverns excavated in phases, which are finally coupled. Geomechanical guidelines were defined and implemented with a risk-based operational strategy, complemented by a geotechnical ground control plan and instrumentation monitoring system that would allow early identification of variations. The focus was on the long-term and overall stability of the excavations. This paper describes the designs as well as considerations for geotechnical ground control and construction. Additionally, the main challenges faced during the excavation stages are summarised, along with additional actions that have supported the stability of this excavation. This project is of vital importance for the future of the El Teniente mine production, and the actions taken to ensure its stability will play a critical role in maintaining this production. Keywords: El Teniente mine, crusher chamber, cavern, ground control, geomechanics 1 Introduction Crushing Chamber 1 is an essential component of the future material handling system for the Andes Norte project and future projects. It is spatially located below the haulage level, and its geological environment is fully considered within the Braden breccias complex, a non-mineralised body in the middle of the El Teniente mine. This crushing chamber is considered to be the deepest cavern at the El Teniente mine, located 250 m below the current operative chambers. It is also the largest, with a total design volume of 74,000 m 3 (Figure 1). Ground Support 2023 – J Wesseloo (ed.) © 2023 Australian Centre for Geomechanics, Perth, ISBN 978-0-6450938-5-8 Ground Support 2023, Perth, Australia 215 doi:10.36487/ACG_repo/2325_14