Adhesive bonding of measurement equipment on impact-driven offshore monopile foundations

Abstract

To a certain extent, adhesive bonding of measurement equipment is very common in science and technology, e.g. adhesive bonding of small-scale strain gauges. Adhesive bonding of the entire equipment for a fully autonomous pile driving monitoring of an impact-driven large-scale foundation structure for an offshore wind farm is a completely new application method. Several offshore wind farms are currently under construction in the North and Baltic Seas. Impact pile driving of the large-scale foundations usually causes much louder noise than permitted by regulations, so methods for noise reduction are necessary. Geotechnical engineers of the TU Braunschweig are investigating combined methods for reducing that noise, and in 2014 they had the opportunity to install measurement equipment for the investigation of dynamic pile deflections during pile driving into three of in total eighty monopiles (length: 60?m, diameter: 6?m) of an offshore wind farm in the German North Sea. Due to certification issues conventional methods of fastening such as screwing or welding were not permitted. Instead, adhesive bonding of all parts (sensors, cables, shielding, recorder/computer) was successfully applied and withstood impact driving with several thousand blows of up to 1200?g (earth gravity). The authors would like to present the concept and preceding tests of the adhesive bonding applied within the research project ‘triad’.