Bearing performance of steel pipe pile in multilayered marine soil using fiber optic technique: A case study

It is important to appraise the performance of the steel pipe pile performance in harbor engineering. The load transfer mechanism and pile-soil interaction could not be clearly understood using the traditional measurement. In this case, fiber Bragg grating (FBG) and Brillouin optical time domain reflectometry (BOTDR) were applied simultaneously at an open-ended steel pipe pile field test in Ganyu Port, China. Results showed that the fiber optic sensing system accurately measured the axial force, side friction, and bearing behaviors of open-ended steel pipe piles based on strain data. During the pile driving stage, the system captured the bending deformation and eccentric load on the upper part of the pile above the mud surface, identifying the relatively large tensile strain at the final stage of driving. For the static load test, the strain and resistance distribution obtained by sensing systems suggested that 80% of pile compression was concentrated in the upper 20 m, and the maximum force was observed at the location of soil surface. The precision of high strain dynamic tests is limited for complex field conditions and model's parameters-setting.