The proposed St. Brieuc Offshore Wind Farm will be located approximately 16km off the northern coast of Brittany, France. The site is within the Massif Armorican comprising shallow Precambrian and Paleozoic rock of the Binic, Roche Derrien et du Minard Formations and the Erquy-Fréhel Group, with a variable cover of superficial deposits. The adopted foundation solution consists of jacket substructures supported by drilled and grouted steel tubular piles. This paper describes the site investigation and integrated ground modelling strategy adopted by Ailes Marines and Atkins to enable informed decisions to be made during the ground investigation and preliminary design stages of the project. A 3D GIS-based observational ground model was developed for the project using several vintages of geophysical survey data, calibrated by the available borehole data, to enable predictions to be made of the stratigraphy at each proposed turbine location. This predictive ground model was used to provide targeted data and assess the representativeness of the acquired ground investigation data across the foundation zones. This paper provides a case study demonstrating the effectiveness of this type of predictive 3D ground modelling technique for enabling targeted ground investigations for offshore sites, including those where rocksocketed pile solutions are being considered.
Jordan Geear, Clement Tam, Andrew Hart, Agustin Bertossa, Indrasenan Thusyanthan and Julien Pitel
Keywords: wind farm, ground model, ground investigation, ground characterisation, targeted data, design risk mitigation
Publisher: DFI