Por: W. Rodríguez, Vicepresidencia de Proyectos, Codelco Chile; M. Jaque, GMT Servicios de Ingeniería Limitada, y J. Vallejos, Departamento de Ingeniería de Minas, AMTC, Universidad de Chile.

Trabajo presentado en el 8° Simposio Peruano de Geoingeniería.

Abstract

The main infrastructure tunnels of the Andes Norte Project, Nuevo Nivel Mina, of the El Teniente Division, Codelco-Chile, are located in a geologically and geomechanically complex environment. The structural geological condition and the surrounding stress field play a significant role in the excavation-induced seismicity. 

This has led to the proposal and implementation of a methodology to analyze the causes of rockbursts in deep tunnels. Rockburst (RB) is one of the critical risks that has had to be managed during the construction of tunnels for the Andes Norte Project, as these are associated with the occurrence of excavation-induced seismicity. The consequences observed from the occurrence of this phenomenon can be extremely severe, including harm to personnel and equipment, as well as the loss of continuity in the tunnel construction process. 

When this occurs, an investigation is carried out to identify the main causes that triggered the rockburst in a specific section of the tunnel. This process improves the understanding of the phenomenon and the surrounding conditions that favor the occurrence of such events, enabling the implementation of measures to manage this risk and mitigate its consequences. 

This article describes a methodology for analyzing the causes of rockbursts in deep tunnels, based primarily on the experience of the Andes Norte Project, where seven rockbursts have occurred in the development of the access tunnels from 2013 to date. The methodology addresses key aspects such as seismicity analysis, geological, geotechnical, and geomechanical conditions, and geometry, along with operational aspects, field inspection, support design and repair planning, and numerical modeling.