Measurement of soil response to laterally loaded piles using distributed fibre optic sensing

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4. Measurement of soil response to laterally loaded piles using distributed fibre optic sensing

The design of piles to withstand strong lateral loads has always been a crucial aspect of geotechnical engineering in the development of offshore wind farms. This applies to both current bottom-fixed structures, typically supported by monopiles or jacket pin piles, and future Floating Offshore Wind Turbines (FOWT), where anchor piles serve as a viable mooring solution. While models predicting pile response have significantly improved over the past two decades, understanding soil behaviour around the pile remains challenging due to the experimental difficulty of accessing soil response along the pile's length. To deepen the understanding of this interaction, large-scale experiments were conducted at Technical University of Darmstadts geotechnical test pit as part of the GEOLAB project. A model pile with a diameter of 0.325 m, embedment depth of 2 m and aspect ratio of 6.2 was installed in dense, compacted sand and subjected to lateral loading. Alongside conventional pile instrumentation, Distributed Fibre Optic Sensing (DFOS) was employed using an 80 m fibre optic cable installed at three levels in the sand around the pile. This innovative approach provided continuous, high-resolution strain measurements, offering detailed insights into soil deformation induced by lateral pile loading. This paper details the experimental setup, the installation of the DFOS system, and an analysis of the monotonic loading test results. The findings demonstrate the effectiveness of DFOS in capturing soil response near the pile, providing valuable information for validating numerical models and facilitating more informed FOWT foundation designs.

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

8 - Monopile design to lateral monotonic loads