ENEL - HPP Los Cóndores

Los Cóndores is a 150 MW HPP, including a 12 km long headrace tunnel (4.6m diam, excavated by D&B and a DS hard rock TBM), a 120 m high surge shaft (6m diam), a 480 m high pressure shaft (2.6m diam), both being excavated using a raise borer machine RBM, and a 1.6 km long subhorizontal pressure tunnel leading to an underground powerhouse accommodating 2 Pelton units. The region is volcanic, with several active volcanoes in the recent geological eras. Maule Laguna volcanic complex is one of the major and the geological formation are essentially dacitic and rhyolitic lava field with rich tuff and volcanic breccia presence in subhorizonal sedimentation and several lava and basalt domes and dikes crossing these formations. Excavation of the upper waterway (HRT) is foreseen in two phases through a central adit by TBM, in order to shorten the time for accessing and execute the vertical works. During the excavation of the HRT lower reach, the TBM got stuck in a cohesionless material, likely the seat of a paleo-basin (syncline) or a paleo-canal within the lava and breccia banks. The services targeted the understanding of the situation, definition of the operations required for the TBM to be safely unlocked from the jammed conditions and option for realizing a bypass around the TBM in case no success was provided by other means. Because of the significant modification of the working program, the evaluation was required of the options for realizing the upper reach of the HRT by other mechanized means (second TBM) or other excavation method, given the logistic conditions at site. Possible optimization of vertical works, in terms of efficiency and realization concept was also part of the required services; in particular, a preliminary study considering 5 alternatives of the scheme combined with different excavation methods options (D&B and/or RBM) were carried out, in order to analyze the possibility to disassociate the construction of the vertical works from the TBM advance and to better manage the geological and construction risks associated with vertical works construction.
Reference location
Maule Region cordillera
Final client
Enel Chile, Ltda
Is Consortium
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Projektierungen Bau; Expertisen / Gutachten; Bauherrenunterstützungen; Spezialstudien