Compacting earthworks at the massive Jirau dam
Despite controversy and engineering problems, work is making progress on the massive Jirau dam project close to the border with Bolivia. The Jirau project, which will have a capacity of 3,450 MW generated by 46 turbines, is currently the largest hydroelectric scheme under construction in the Americas.
The Jirau dam complex will comprise a rockfill dam, 35 m high and 550 m long, flanked by two compacted earth dikes, one 930 m long and the other 1,140 m long. The reservoir will cover an area of 258 km². Powerhouses on each bank will house the turbines.
Jirau’s massive site employs an estimated 16,000 workers, most of whom are housed in camps at the site itself, and work is being carried out on a 24 hour basis.
Construction is being undertaken by the consortium ESBR Sustainable Energy of Brazil, formed by companies GDF Suez of France(50.1%), Eletrosul (20%), Chesf (20%) and Camargo Correa (9.9%). Camargo Correa, one of the country’s largest contractors, is undertaking the civil works.
Jirau, together with the Santo Antonio hydroelectric project being constructed adjacent on the same river, where a fleet of Dynapac machines is also working, is considered a crucial element for the future supply of electricity.
Brazilian contractor Camargo Correa is using a fleet of Dynapac vibratory compactors, including a Brazilian-built CT 300 tamping roller, for constructing the earthworks at the Jirau hydroelectric project.
A new Brazilian-built Dynapac CT 300 static tamping roller is amongst the fleet of Dynapac equipment being used by contractor Camargo Correa One of the primary functions of the articulated machine, which is fitted with padfoot drums to the front and rear, is to compact the soil that will form the floor of the reservoir which will build up directly behind the dam.
The CT 300 is the only one of its kind on the site, the other models being mainly CA600 single-drum vibratory compactors.
Luiz Paulo Santos, Camargo Correa’s manager for mobile equipment, said that the CT 300 was chosen for its manoeuvrability and speed of working, as well as for its high availability to the work.
The compactor weighs 21 t and is specifically designed for compacting cohesive or semi-cohesive soils over large areas. As a static tamping roller, high speed is required for optimum compaction, and the CT 300 can travel at a maximum speed of 21 km/h, forwards and backwards.
Each of the four drums is fitted with sixty 185 mm high pads,giving a contact area of 200 cm², adding up to an average production capacity of 800 m³ per hour.
With a steering angle of 40º to either side and a turning radius of 6.3 m, the machine can work fast around other equipment and cope with irregular areas.
The Madeira River is the largest tributary of the Amazon, with Jirau located 130 km from the nearest town, Porto Velho. The Santo Antonio project is located just 5 km outside of Porto Velho. Work began on Jirau in 2008 and power generation is expected to begin in 2012. The project is expected to operate at full capacity by October 2016.
Engineering model of the Jirau dam project prior to construction works beginning.
© Edgar Trierweiler