Pile run prediction utilizing SRD methods

Abstract

The global increase in energy demand coupled with the need to accelerate energy transition has heightened the need for sustainable energy sources, such as wind energy. Offshore wind energy has a number of advantages when compared to onshore, including less turbulent wind, higher wind speeds and less land dispute with other activities, hence playing an important role in this process. However, its foundation design is challenging, particularly under complex geotechnical conditions. One critical risk during pile installation is pile run, a sudden uncontrolled penetration of the pile into the soil that can cause severe financial loss, installation delays and structural damage to the crane and installation vessels.
This research investigates pile run by focusing on the limitations of current static Soil Resistance to Driving (SRD) prediction methods and the influence of soil consolidation on pile driveability. Traditional SRD approaches, such as Alm and Hamre, that relies on CPT data are reviewed critically and their limitations are assessed. Studies show that while this method performs well for clean sands and clays, it is unreliable for soil mixtures and intermediate soils, where discrepancies arise due to different consolidation conditions during CPT testing and driving.
To address these limitations, the study evaluates penetration rate effects by comparing drainage conditions during CPT testing and during driving, using GRLWEAP software to calculate the driving velocities. Adjustments are then made to the SRD predictions applying reduction factors that represent the changes in drainage conditions and loss of soil resistance due to consolidation effects.
This study shows that in regions where unpredicted pile runs occurred the adoption of those reduction factors help in the identification of pile run risk regions. However, a more extensive database of soil tests considering different soil density, fines content, and consolidation state should be analyzed to propose definitive reduction factors that can be widely used for different soil conditions around the globe.