Limited by geological survey methods, processes, and cost, it has long been a difficult thing to accurately detect the position of landslide slip surface and monitor the landslide internal deformation. Fiber Bragg grating (FBG) sensing technology has been widely used in geological engineering and geotechnical engineering due to its high-precision property. In this research, FBG sensing technology was applied to the monitoring of landslide internal deformation in Toudu, Chongqing, China. The in situ monitoring by FBG accurately determined the position of the landslide slip surface. Based on the relationship between fiber grating strain and deflection, the formula between landslide internal deformation and fiber grating strain was obtained, and the rationality of the formula was verified by the monitoring data of surface displacement. Finally, the internal deformation at the monitoring point of the Toudu landslide was calculated and the mechanism of the landslide was analyzed.
Deep displacement monitoring is an important means to monitor the deformation of slope, landslide and deep foundation pit. Traditional deep displacement monitoring uses manual inclinometer, which is time-consuming and laborious, and has large manual operation error, so it is impossible to realize automatic monitoring. It is urgent to adopt new technical means to make up for these shortcomings. Based on fiber Bragg grating sensing technology and beam bending theory, this paper establishes the calculation formula of fiber Bragg grating deep inclinometer, which can calculate the deep displacement curve of inclinometer through the change of fiber Bragg grating center wavelength; The strain sensitivity coefficient of fiber Bragg grating is calibrated by indoor calibration test. The experimental results show that the center wavelength of fiber Bragg grating has a high correlation with strain, and the relationship is linear. The strain and displacement of inclinometer tube are monitored and compared by indoor model test. The test results show that the displacement error calculated by fiber Bragg grating is 2% ~ 12%, which can meet the needs of deep displacement monitoring. The relevant conclusions provide a certain reference for the research of fiber Bragg grating deep displacement monitoring.
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