Design and Construction of Cerro Del (A)guila Gravity Dam in Peru

摘要

Cerro del (A)guila project in Peru represents the final step of the Mantaro River major hydropower scheme cascade development.This 520 MW hydropower scheme,presently under construction,will include an 88 m high and 270 m long RCC gravity-arch dam equipped with 6 mobile gates providing a total capacity of the surface spillway of around 7 000 m3/s.The bottom outlets increase the total discharge capacity of the dam up to 12 000 m3/s.The volume of the dam is approx.0.5 Mm3 with a relatively high percentage of vibrated concrete due to the fact that the 6 bottom outlets are large and require high strength concrete.The bottom outlets are in fact designed to allow an easy annual flushing of the reservoir knowing that the sediment yield is around 3.5 Mm3/year.A special attention was also given to the design of the upstream face of the dam in order to confirm its behavior during earthquakes as the site is considered seismically very active.This dam is equipped with galleries for the foundation consolidation grouting.These galleries were designed in order to accelerate the construction process allowing consequently the treatment of the base of the dam without interfering with the construction activities.Several other concepts were also applied that allowed rapid placement of the RCC paste.Concrete placement is mainly carried out using a high capacity blondin combined with transport trucks and steel chute.The mix design of the RCC was optimized using full scale test sections.With a low percentage of pozzolanic content up to around 20％,temperature rising during the hydration of the concrete was a concern.Extensive investigations were thus considered in order to reduce the cement content while respecting the design strength.In this paper an outlook of the main design features of the dam is provided together with some major highlights regarding the optimized mix design,the construction process,and concrete placement.