Foundation Design Helps To Save Resources

«To work with CTE Wind as designer was nice. The speed of response and reliability of the planning has been a winning experience for us.»

Arjan Louwerse from H4a Windenergie B.V.

Coöperatie Zuidenwind has poured the concrete for the foundation in Heibloem in the Netherlands and created the basis for the installation of their wind turbines. The foundation design and calculation for this project was done by CTE Wind Civil Engineering. The expert in foundation design WTG suggested their Soft-Spot® instead of a typical pile foundation.

Heibloem (NL) / La Richardais (FR) – The Netherlands soil consistsof unconsolidated, very young sediments. Due to the proximity of the low-lying part of the European continent, the basin of the North Sea, the bottom rarely rises higher than 30 m above sea level. In the areas along the coast (provinces of Groningen, Friesland, Noord-Holland, Zuid-Holland, Zeeland) the surface soil layers consist mainly of clay deposits. In the west of the Netherlands the clays are replaced by lowland moors (peat). To sum up: in the Netherlands, pile foundations are mandatory for wind turbines because of the concentrated forces occurring on little surface area. Except in Heibloem, where the ground is exceptionally stable. So good, in fact, that CTE Wind offered its resource-saving Soft-Spot® instead of the usual foundation.

Soft-Spot® in the Netherlands

The Soft-Spot® was developed by CTE Wind’s engineering team and is implemented in various countries around the world. «It was simply the most economical foundation we could choose », Arjan Louwerse from H4a Windenergie B.V. says. He is the project manager for Coöperatie Zuidenwind wind turbines. This foundation design optimizes the use of resources and helps to save up to 15 % of concrete and 2 to 5 % of reinforcement steel. In some cases what is even more important than the costs is the available space : with Soft-Spot® you need less surface for the foundation. This reduces the time and excavation costs. «The philosophy to reduce the costs of the Soft-Spot® was also a good point of discussion with our client. From the beginning we had a good feeling with the design», he explains.

In fact thanks to the new design the outer diameter of the foundation was 1.1m smaller compared to a typical foundation design. This resulted in a reduction of 11 % of concrete and 3 % of steel – or more precisely about 100m3 of reinforced concrete. «To work with CTE Wind as designer was nice. The speed of response and reliability of the planning has been a winning experience for us», Louwerse added. In spring 2020 the wind turbine will arrive together with the largest blades ever installed onshore in the Netherlands. (ctewind)