Experimental study on feasibility of fiber Bragg grating-based foundation deformation monitoring

A new method was proposed to measure strain distributions and understand deformation of ground soil using fiber Bragg grating (FBG) technique in order to solve the problems of low monitoring efficiency, large error and low accuracy in traditional ground deformation monitoring. A plane-strain model test of loaded sand foundation instrumented with embedded FBG sensors was conducted. The particle image velocimetry (PIV) technique was used to obtain the strain distribution of the model foundation behind the sidewall of the test chamber. The test results show that the FBG sensors can capture the accumulation of internal strains within the soil mass with high sensitiveness under different loading levels. The characteristics of the measured strain distribution agreed well with the PIV results, truly reflecting the deformation of failure patterns of the model foundation. The feasibility of applying FBG fiber optic monitoring technique to foundation deformation monitoring was preliminarily verified. Results indicate that PIV can be used as an auxiliary tool to validate or calibrate the FBG strain measurements. The discrepancy between the strain readings measured by these two methods is due to several factors, such as experimental errors, deformation compatibility of the sensors and photographic quality. © 2017, Zhejiang University Press. All right reserved.