Installation of novel suction bucket foundation with new modular geometry in a large-scale set-up

This paper investigates a modular bucket foundation design developed for large offshore wind turbines. Instead of the regular round shape, the modular bucket consists of trapezoidal profiles bolted together and additional stiffeners attached to the inside skirt. The design is more cost-effective and gives much higher buckling resistance during installation compared with the standard round bucket, which serves as a reference point in the research. The paper includes both jacking installation and suction installation tests performed on a large-scale set-up at Aalborg University. The installations took place in sand of varying relative density. Each test consists of measurements for the applied force or suction and the excess pore pressure around the bucket skirt with increasing penetration depth until full installation. Results indicate that regardless of the significant increase in soil penetration resistance of modular bucket measured during jacking installation, the required suction for installation in different sand conditions is very similar for both models. The data are compared with a cone
penetration test (CPT)-based method for the calculation of soil penetration resistance. The method is adjusted according to the experimental results supported by finite-element method analysis.