Abstract
In order to overcome the shortage of the existing fiber grating displacement sensor in the process of measuring bidirectional deformation of the foundation pit, which are the reduction of precision and the decrease of the range, a Fiber Bragg grating-based wire-pull bidirectional displacement sensor is designed. There are two wedge-shaped sliding surfaces and an integrated equal-strength beam structure, which make the sensor have the advantages of anti-sliding interference and high sensitivity of beam deflection displacement measurement. The sensor prototype is manufactured and the related performance tests show that the sensitivity of the sensor is 11.921731 pm/mm in the range of −100 mm to 100 mm, and the correlation coefficient of the fitting curve has reached 0.9996. Compared with the theoretical calculation value, the measured wavelength drift of the full scale deviates by about −0.92% and 0.42%, which can meet the accuracy requirements of structural health monitoring of major facilities such as civil engineering for displacement and deformation measurement. Four calibrated displacement sensors are installed on the top beam of the foundation pit of Beijing Daxing International Airport, the world's largest aviation hub, to monitor the deformation of foundation pit in real time. The reason of the displacement change of each monitoring section is analysed and the actual working condition on the site is checked. The effectiveness of the FBG bidirectional displacement sensing in the displacement monitoring of foundation pit engineering is verified.
Published Version
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