Wind farm Muttenz

In Muttenz near Basel, the energy company aventron is planning to erect an Enercon E-115 wind turbine with a height of up to 190 m (hub height 120 m). Gruner's Geotechnical Engineering department was allowed to work on the project as general planner in the preliminary project.

The facility is to be located in the intermediate area between the A2 national road and the SBB track field. The aim of the project was, among other things, the feasibility analysis of possible foundation variants. The logistics of heavy and special transports for the construction of the facility were also included in the feasibility study. The preparation of a verifiable preliminary structural analysis of the foundation of the wind turbine was necessary for the approval by the local residents. 

At the site between the SBB track field and the national road, there is a geological fault zone in the deeper subsoil and a former gravel pit near the surface. The area is also known for karst cavities. Therefore, a multi-stage geological investigation program had to be developed in order to ensure a safe foundation for the wind turbine. For the foundation of the wind turbine in the existing ground, three different variants (vibro-compaction, pile foundation, shallow foundation) were designed, each with special measures for the location and treatment of karst cavities, which ­meet both the stability requirements ­and the stringent serviceability requirements ­during the operation of the turbine. In addition to the structural design of the foundation variants, the cost and construction times ­were also analysed and compared with the respective advantages and disadvantages.

The erection of a wind turbine of this size requires considerable logistical effort both during transport to the site and during erection on site. In addition to the clarification of possible transport routes, a logistics concept was designed for the effective use of the limited space available during the construction of the foundation and the erection of the wind turbine at the site.

The services of Gruner AG:

• Technical planning of the pre-project phase
• Deep foundation and shallow foundation incl. soil improvement
• Deformation prognosis of the foundation variants under static and dynamic actions
• Logistics planning
• Cost estimate

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