G3 Projects: Design and Construction Supervision
The Cahora Bassa Dam in Mozambique is a 171-metre-high arch dam built in the Zambezi Gorges from 1969 onwards and commissioned in 1979. The underground power station, built on the right bank downstream of the dam, comprises five units with an installed capacity of 2,000 MW, making it the second most powerful in Africa after the Aswan Dam.
The access road to the underground power station runs alongside the high cliffs that form the Zambezi Gorges. It is therefore constantly exposed to the risk of rockfall associated with the ‘spalling’ typical of granite materials. In order to secure this access route and in anticipation of the planned construction of a second power station on the left bank, HCB, the dam operator, launched a major operation to secure the cliffs on the right bank (approximately 400 m in total length and a height of around 100 to 120 m).
Terrasol assisted (in collaboration with Hydrogéotechnique’s cliff division) the company Hydrokarst during the tender phase. Hydrokarst was awarded the contract for €13 million, and we therefore continued to support them with design and construction supervision, still in a joint venture with Hydrogéotechnique.
Some rock masses are secured by the construction of footings made of in-situ reinforced concrete: we studied the anchoring and reinforcement requirements for these unique structures. The challenge lay in defining the reinforcement methods for a mass with an irregular geometry, with access via ropes only and using materials available on site. We then visited the site to assist Hydrokarst’s staff with the reinforcement of the first abutment and to verify that the work was carried out correctly (cover depth, compliance with minimum and maximum cover requirements, etc.).
Cost of the works
€13 million
Value of services
€45,000
Client
HCB
Key figures
- 171-metre-high arch dam
- Capacity of 2,000 MW
- 120 m high cliff
