Long Service Life in Aggressive Environments: DYWIDAG Strand Anchors Stabilize Caniçada Dam
The Caniçada Damm on the Cávado River in north-western Portugal was built in 1955. The 246m long arch dam forms part of the Cávado-Rabagão-Homem cascade system which produces energy in 8 different hydroelectric power plants. The Caniçada Dam is 76m high and has an active capacity of approx. 150 million m³ of water that can be used to generate 32GWh of electrical energy.
In order to meet recent requirements of the Portuguese dam safety legislation, the operator EDP conducted a safety assessment of the dam. The analysis concluded that an additional spillway was needed.
EDP awarded Mota-Engil Engenharia e Construção S.A. the contract for the construction of the new overflow weir consisting of a control structure equipped with two radial gates. The gates are connected to a 200m long tunnel that ends in a ski jump structure. If there is a large amount of rainfall, water can be diverted via the ski jump into the absorption basin by opening a stop valve.
As DSI had already successfully contributed to other dam projects, the owner invited DSI Portugal to provide an efficient and long-term solution to stabilize the slopes on both sides of the spillway.
For this purpose, DSC produced and supplied 82 permanent, 4 strand, double sheathed, TWIN-Corr System DYWIDAG Strand Anchors. The anchors were pregrouted in the factory and supplied to the jobsite together with the necessary anchor heads. Afterwards, the general contractor installed the DYWIDAG Anchor Systems in the slopes.
As a durable system for permanent use with a service life of more than 100 years, the TWIN-Corr System proved to be the best solution for such a technically demanding project. The DYWIDAG Strand Anchor System has two plastic sheaths in the bonded length, thus ensuring a permanent tie back in structures that are located close to the water and therefore highly susceptible to corrosion.