World Tunnel Congress 2014 – Tunnels for a better Life. Foz do Iguaçu, Brazil. The construction of t
J.L. Orgaz, F. Peinado
COBRA Infraestructuras Hidráulicas (ACS Group), Madrid, Spain.
J. M. Galera, D. Santos, C. Quiroga and S. Espina
Subterra Ingeniería, Madrid, Spain.
ABSTRACT:
The hydroelectrical project Renace II is located at Cahabón River, in the Alta Verapaz Department, Guatemala The owner is Recursos Naturales y Celulosas, S.A. (RENACE, S.A.) that is part of Corporación Multinversiones, and the construction contract was awarded to COBRA Infraestructuras Hidráulicas. Renace II will provide 112 MW using a gross head of 335 m and a flow of 40 m3/s. This paper aims to summarize the main aspects of the design process that have been carried out for the underground works involved in the project. Also the main aspects of the construction phase are shown. The main difficulty has been the intersection of the tunnels with cavities originated by karstic processes in the limestones of the Coban Formation. The construction method and the equipment used are providing good advance rates and optimum safety condition in the excavation and support of a large underground project.
1 Introduction
The Renace II project is a hydropower project that is under construction by the company COBRA. The project is located at Cahabón River in the Alta Verapaz Department of Guatemala. Figure 1 shows the location of the project.
Renace II is the second of three elements in the use of Cahabon River. The first stage, Renace I, has been already built and is operating gross head of 210 m. In this moment a regulating reservoir is projected whereby the production is envisaged to be increased to 60 MW.
The hydroelectric project Renace II is located immediately downstream of the Renace I powerhouse.
Renace II will provide 112 MW using a gross head of 335 m as its elevation varies from 974 m at the intake to 640 m at the powerhouse, with a flow of 40 m3/s.
The underground works involved in this project basically consist of a low-pressure tunnel, a high-pressure tunnel and a small free flow mud tunnel. Their main characteristics are summarized in Table 1
