Optimising back analyses of offshore pile driving in weak rocks with a data-driven approach

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4. Optimising back analyses of offshore pile driving in weak rocks with a data-driven approach

The driveability of foundation piles for offshore wind turbines through weak rock formations is subject to significant uncertainties, which often manifest into project risks associated with pile runs or pile refusals. While an improved understanding of the Soil Resistance to Driving (SRD) can be obtained by back analysing historic driving data to manage these installation risks, such back analysis is not straightforward and is in fact a highly non-linear problem governed by a large number of factors. Signal matching analyses provide valuable insights into the SRD, but it is often only possible to perform on a small subset of instrumented piles. On the other hand, extensive collections of blow count records exist which can be harnessed to enhance and inform SRD predictions. This paper investigates the case study of the Wikinger Offshore Wind Farm (OWF) in the German Baltic Sea with piles driven through glacial till and chalk. An optimisation methodology is proposed, utilising blow count records in chalk stratigraphy to assess and enhance the performance of existing SRD methods. The methodologies for back analysing the blow count records and optimising the SRD parameters across all pile locations are discussed and demonstrated through an example. Attention is drawn to potential pitfalls in performing such analyses, as well as more practical aspects including data cleaning and pre-processing.

5th International Symposium on Frontiers in Offshore Geotechnics (ISFOG2025)

7 - Pile design and installation in challenging soil conditions: glauconite, carbonated soils, cemented soils, gravels and rocks