Adhesive Bonding and Sealing of Additional Equipment on Foundations of Large-Scale Offshore Wind-Energy Turbines Withstanding Pile-Driving Operations

摘要

Renewable energy is massively on the rise in different parts of the world, and offshore wind-energy farming is now competing for the first time with traditional power stations because of a basic continuity and amount of electrical energy. The relatively new kind of large-scale construction in the sea bed has to withstand the elements for decades, and the certification is based on a number of assumptions; therefore, wishes for changes or additional equipment on the foundations of offshore wind turbines do not comply with certification rules because thermally or mechanical interventions in the structure or the protection coatings might initiate an early damage scenario. Adhesive bonding of additional equipment on foundations is a solution for avoiding such certification problems, but this solution faces two major challenges: withstanding the initial-impact pile driving with huge mechanical accelerations and the more common long-term exposure to sea water, tidal and storm waves, and seasonal temperatures throughout the full lifetime period. Well-performing bonding and sealing over a long period of time presumes the successful survival of the initial high-energy impact pile driving without any damage, and this unique period of just a few hours with several thousand repeating blows can be seen as an enormous encroachment, especially for larger masses bonded to the pile walls. Suitable adhesives and coatings must show a special kind of durability for this initial operation. This paper presents experiences and results from experimental investigations of an adhesive bonding and sealing approach for installing measurement equipment on the vertical walls of different monopile foundations in offshore wind farms in the European North Sea.