Analysis of pile load transfer using optical fiber sensor

Distribution of axial strain in model piles was measured by Fiber Bragg Grating (FBG) sensor to investigate a possibility of measuring and analyzing the load transfer mechanism of pile foundation by Fiber Optic Sensor (FOS) system. Since FBG of different wave lengths can be multiplexed in an optical fiber, the installation of sensor system and the measurement of strains are relatively simple compared with the system consisted of strain gages. In this study, FBG sensors and electric strain gages were embedded in the piles and the distributions of load transfer measured by two sensor systems were compared. It was observed from the test results that the magnitudes of axial load measured by both systems showed insignificant difference and that the distributions of axial load by FBG were smoother than those by strain gage. Under the environments of laboratory testing, survival rate of embedded FBG system was higher than that of strain gage. Therefore, it was concluded that the use of FBG sensor has a great potential for the measurement of pile load transfer with accuracy.