ABSTRACT
This paper reports on large scale tests of monopile foundations for Offshore Wind Turbines (OWT) to be conducted in test site in Zeebruges, Belgium, in the framework of the SAGE-SAND project (Soil ageing around OWT foundations – from operational response to decommissioning). The project aims to investigate the evolution of the soil mechanical properties with time, and the alternative use of vibratory driving, to hammering, for installation and decommissioning of monopiles. Four hollow steel monopiles will be installed, by impact hammering and by vibratory driving, at a location where the soil conditions are representative of the Belgian sector of the North Sea. At selected time intervals during the project, the piles will be subjected to lateral loading at a fraction of their lateral capacity. Both the soil ageing effects and the influence of the installation method will be investigated. Herein an overview of the SAGE-SAND field testing program is presented, along with geotechnical information obtained from standard in-situ tests. Cone Penetration Tests (CPTs), as well as geological information and existing boreholes in the vicinity of the project are shown. Available correlations and empirical relationships from the Belgian practice are used to infer the soil stratigraphy and relate CPT data to soil properties necessary to perform predictive numerical simulations. Continuous in-situ tests such as cross hole tests and CPTs to the proximity of the piles throughout the duration of the project will allow the examination and the analysis of the soil ageing process.
