The El Teniente Mine of Codelco is one of the largest underground mine operations in the world. The mine employs massive mechanised panel caving methods with pre-undercut variants to extract copper-molybdenum ore, producing 140,000 t/d, mainly of primary copper ore. In the context of a study of rehabilitation measures for collapsed zones at the Esmeralda mine, which is one of Teniente´s most important operations, a preliminary assessment of the post-collapse pillar's rock mass condition was carried out, allowing the characterization of the damage zone surrounding the drifts and some insights into the likely pillar's rock mass damage development. The paper outlines these findings and discusses some underlying factors that may also have influenced the process. GeneralThe present operations in El Teniente Mine include six productive sectors, located at different elevations, including the Esmeralda, Reservas Norte, Diablo Regimiento and Pipa Norte, which extract ore from the porphyry copper deposit that surrounds the Braden Breccia Pipe, a massive volcanic intrusive body roughly circular in plan view and an inverted cone in depth, with variable diameter (maximum 1,200 m) ( Figure 1).Two massive mine collapse events have taken place between the years 2001 and 2010 at the Esmeralda Mine, affecting large production areas and generating severe rock mass damage of the undercut and extraction level pillars. In the context of a study of rehabilitation measures for these collapsed zones, a preliminary assessment of the post-collapse pillar's rock mass condition was carried out, allowing the characterization of the damage zone surrounding the drifts and some insights into the likely pillar's rock mass damage development. The paper outlines these findings and discusses some underlying factors that may also have influenced the process. Geological settingThe main lithologies found in the mine orebody include andesite, diorite and hydrothermal breccias of the Miocene era. The main structural features consist of a stockwork of multi-directional sealed veins and veinlets, which are principally cemented with anhydrite, quartz and sulphides. The specific geology of the Esmeralda Mine corresponds to the El Teniente Mafic Complex (CMET or Andesites), a volcanoplutonic complex composed by darkgrey to black basalt, andesite, diabase sills, and gabbro intrusions flooded with fine grained biotite, which is subdivided in two distinct zones, denominated CMET hanging wall (Hw) and CMET footwall (Fw), with slightly different geomechanical behaviour. The CMET has been intruded by major ore bodies: Felsic Porphyry Units (Diorite and Latite Porphyries) and Breccias units (Breccia Braden T-5 PILARES T-4 SUR T-3 ISLA HAULAGE LEVEL TEN-8 RENO N Fig. 1. El Teniente Mine -Productive sectors plan and view (Esmeralda Mine marked in the red circle)

The mining complex Chuquicamata, of the National Copper Corporation of Chile (CODELCO), is located in the Atacama Desert, 1, 650 km north of Santiago, and 2, 870 m above sea level. Since the large copper ore reserve that lies below the “Chuquicamata” open pit (Fig. 1) will no longer be economically feasible to mine from the end of this decade, the mine is currently developing the required infrastructure to switch the operation to an underground mine type, where the block caving method with macro‐blocks will be used to mine out copper ore. The future mine will count with four production levels, corresponding to one of the largest underground mining operations in the world, with a production rate of about 140, 000 t/d. This article presents design aspects of the permanent underground infra‐structure works, which encompass several deep and steep tunnels and vertical shafts for the future mine access and operation.Der Bergbaukomplex Chuquicamata der National Copper Corporation of Chile (CODELCO) liegt in der Atacama‐Wüste, 1.650 km nördlich von Santiago und 2.870 m über dem Meeresspiegel (Bild 1). Ab Ende dieses Jahrzehnts wird der Abbau der Lagerstätte im Tagebau nicht mehr wirtschaftlich sein. Daher werden derzeit die notwendigen Infrastrukturanlagen errichtet, um den Betrieb auf Untertagebau umzustellen, wobei das Kupferz im Blockbruchbau mit Makro‐Blöcken abgebaut werden soll.? Das Bergwerk wird künftig über vier Produktionsebenen verfügen und mit einer Produktion von etwa 140.000 t/d zu einem der größten Bergwerken der Welt zählen. Dieser Beitrag stellt einige Planungsgesichtspunkte für die dauerhafte unterirdische Infrastruktur vor, die mehrere tiefliegende und steile Tunnel und Vertikalschächte für die Erschließung der Lagerstätte und den Betrieb des Bergwerks umfasst.

In the early year 2000, the Santiago's subway network was comprised of not more than 40 km and 46 stations with only about a half of its network being underground construction, mainly cut and cover boxes. Nowadays, with the additional 17.5 km of new line extensions (Line 1 and 5), the subway network will achieve a considerable expansion reaching a total length of 104.5 km and 108 stations, with over 60 km of shallow mined tunnels and more than 70 underground stations. The construction of the new extensions of Line 1 (3.3 km) to the East and Line 5 to Maipu/West (14.2 km) have started in the beginning of 2007 and are planned to be completed in 2009. The mined tunnel sections of both lines include twelve large shallow underground stations and several intermediate ventilation and emergency exit shafts and tunnels. The present article describes some relevant aspects associated to the design and construction of shallow tunnels for the Metro Santiago and gives an insight into the current ongoing construction works of the new Line 5 extension.

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