Improving axial pile design through full-scale field testing and fibre optic sensing

Recent advancements in fibre optic sensing have increased the range of monitoring techniques available for measuring the axial response of full-scale piles. For instance, distributed fibre optic sensing gives a continuous measurement of normal force with depth in a pile, meaning the shaft resistance of a pile can be accurately quantified in each soil layer. Other fibre optic sensing methods, such as Fibre Bragg Gratings, have been shown to provide accurate and robust high-frequency measurements of pile installation. With these improved measurement techniques, detailed insights can be obtained into not just the geotechnical response of the pile, but also the structural response. Presented in this paper is some first-hand fibre optic data collected from axial load tests on piles founded in dense to very dense sand, ranging from driven piles to screw displacement piles. Using fibre optic sensing, key insights could be gained into both the structural and geotechnical response of these piles at large base and shaft resistances, facilitating changes to CPT-based pile design methods at a site-specific and nationwide level.