Error analysis and experimental research of joint fiber-optic displacement sensor based on shear lag model

•A joint fiber-optic displacement sensor base on OFDR and shear lag model is proposed.•Monitoring errors caused by strain transfer are considered.•The feasibility and effectiveness of the sensor are verified in the test. Landslide displacement monitoring is an efficient method to mitigate casualties and economic losses caused by landslide disasters. In recent years, distributed fiber-optic sensing technology, due to distributed and long-distance advantages, was widely used in subsurface displacement monitoring of landslides. However, existing fiber-optic displacement sensors has a large monitoring error when the landslide has multi-sliding surfaces. Aiming at solving this issue, a new joint fiber-optic displacement sensor which can achieve accurate displacement monitoring, was designed. Its measurement error was analyzed and the feasibility was demonstrated by theory and laboratory experiment. Based on the shear lag model, the error caused by strain transfer was studied by fiber-optic cable pull-out experiment. Finally, the feasibility of the sensor was verified by calibration experiment and soil shear experiment. The results show that the displacement sensor has high sensitivity and accuracy, and can realize distributed displacement monitoring inside the slope with multi-sliding surfaces.