Abstract: The optical fiber testing technology is stringing the fiber Bragg grating (FBG) by naked fibers in order to construct the multi-point sensing testing system, which has the advantages such as higher precision, stronger anti-interference ability, higher spatial resolution and continuous data acquisition. In this paper, the fiber grating sensing technology was applied to monitor the glass fiber reinforced polymer (GFRP) anti-floating anchor, and the strains at the interfaces of anchor-anchorage body, anchorage body- surrounding rock, and within anchorage body were measured, achieving the multi-interfacial and full-length measurement of GFRP anti-floating anchor. The results showed that the fiber grating sensing technology was able to accurately record the strain change of GFRP anti-floating anchor in the entire duration of the pull-out test. Additionally, the results revealed the distribution law of axial force and shear stress within the anchorage body and at the interfaces of anchor-anchorage body, anchorage body-surrounding rock with the change of applied load and depth. The transfer depth of the load and the influenced range of the shear stress were different at different interfaces. Generally, the measurement technology and sensor embedding method have many advantages, showing broad prospects in geotechnical engineering research and applications.

Key words: metro, GFRP anti-floating anchor, fiber grating sensing technology, micro FBG strain sensor, anchorage body, shear stress