DFOS for pull-out testing of self-drilling passive anchors in port reinforcement works

Port infrastructures undergoing deepening or dredging works often require structural reinforcement to withstand the increased earth pressures acting on quay walls. In such contexts, self-drilling passive anchors are increasingly replacing traditional active tie rods, due to their faster installation, higher durability, and reduced maintenance requirements. However, their design and validation demand accurate testing methods capable to describe the full load-transfer mechanism along the bar. Conventional pull-out tests instrumented with strain gages provide reliable strain measurements but only at discrete locations. Distributed Fiber Optic Sensing (DFOS) technology overcomes this limitation by enabling continuous, high-resolution strain measurements along the entire anchor length. This work presents results of a full-scale pull-out test on a passive self-drilling anchor used to reinforce a quay wall within a port area. The test was instrumented with both conventional strain gages and DFOS cables integrated along the steel bar, allowing a direct comparison between the two measurement systems. The distributed strain profiles allowed the progressive mobilization of bond stresses along the anchor to be clearly identified, providing a more comprehensive description of the mechanical response of the anchor compared with traditional strain gages. The results demonstrate the potential of DFOS as a powerful tool for the experimental validation and future monitoring of geotechnical reinforcement systems in marine infrastructures.