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Novel Fabrication Methods for Wind Turbine Foundations

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It is anticipated that the market for offshore turbines will significantly outstrip the current manufacturing capacity. This work examines a new and innovative fabrication process for offshore wind turbine foundations which has the potential to allow the necessary production capacity to be met.

Several foundation concepts are being considered for the next generation of offshore turbines, including monopiles, tripods and braced jacket structures. All are manufactured from tubular steel sections. Typically, these are fabricated by rolling thick plate and welding longitudinally to produce cans and then joining the sections together with circumferential welds. Rolling thick plate (>100mm) requires heavy rolls and hence high capital investment, limiting the number of facilities capable of carrying out the process. It is also a time consuming operation and the length of each can is restricted by the width of the rolls and plates, commonly to 3-4 metres. The novel multi-faceted design proposed in this work is fabricated from strips of flat plate welded together longitudinally, hence eliminating the rolling step. This allows sub-assemblies of greater than 10m in length to be manufactured, reducing the number of circumferential welds necessary in the foundation. This approach is enabled through the use of rapid, thick-section welding for the longitudinal seams.

This work has considered the geotechnical and structural aspects of the proposed design concept. The entire production route has been examined in terms of performance, logistics and economics, in order to determine the viability of the multi-faceted approach.

The multi-facetted design concept
A 5:1 scale model of a multi-facetted foundation, fabricated using EB welding (length 2m)
Advanced pile-soil model
A local vacuum EB welding head developed to weld the corners of the multi-facetted structure

Project Objectives

To prove an innovative multi-facetted foundation design concept and demonstrate advantage over conventional monopiles in terms of:

  • Geotechnical requirements
  • Structural performance
  • Fabrication route
  • Production capacity and associated costs
  • Design features

Project Deliverables

  • Definition of design criteria for a multi-facetted pile
  • Demonstration of electron beam (EB) welding a multi-facetted segment with a local vacuum welding head
  • Fabrication and piling of a scale model multi-facetted pile
  • Report on modelling of grouted connections
  • Report on applicability of fabrication process to emerging foundation designs
  • Model of production facility layout and process cost analysis

Project Summary

Modelling of design and installation

Modelling of the foundation design will be carried out. The structural performance, geotechnical requirements, installation implications and certification will be considered resulting in a design specification for the multi-facetted  foundation.

Development of advanced EB welding technique

Local vacuum EB welding with a sliding seal will be developed to enable welding of large foundation components. The challenge is to develop a seal to accommodate corner welds, which is sufficiently robust for industrial application. The developed process will be demonstrated on corner welds.

Fabrication of scale models, piling trials and testing

A 5:1 scale model will be fabricated to demonstrate the potential of the fabrication route and to promote the mf design. The scale model will be instrumented and performance data will be collected as the model foundation is piled into the ground.

Modelling of the grouted connection

The grouted connection is a major industry issue. The effect of the multi-facetted design on the grouted connection will be considered and any resulting design changes identified.

Assessment of the suitability of novel foundation designs

The benefits and limitations of the multi-facetted approach will be identified. Consideration will then be given to the applicability of the concept for fabricating emerging designs (eg. those in the Carbon Trust Offshore Wind Accelerator Programme). 

Modelling of production facilities

Proposed production facilities will be modelled to demonstrate how fabrication will be carried out industrially. The viability of the process will be determined in terms of practicality and cost analysis.

Project partners

For more information please email: