Study On Surface-deep Deformation Monitoring And Stability Of Slope Based On Fiber Bragg Grating Sensing Technology

Landslide volume prediction is an important topic in landslide research,and accurate identification and determination of the morphological characteristics of the landslide surface is the basis for landslide volume size determination and disaster prevention and control.At present,the methods for determining the landslide surface are mainly field engineering survey and numerical simulation,each of which has certain limitations.In recent years,Fiber Bragg Grating sensing technology is widely used in engineering monitoring because of its advantages of long-distance transmission,anti-electromagnetic interference,high sensitivity and high resolution.Based on this,this paper took the slope displacement monitoring as the entry point,used FBG sensing technology to collect monitoring data in real time to design a new displacement sensor,and combined Fiber Bragg Grating deep strain tube(FBG strain tube for short)to build a slope displacement monitoring system,and used theoretical analysis,calibration test,numerical simulation and model test,etc.,to conduct research on the method of determining the slip surface based on the slope displacement monitoring information.This paper provided new ideas and experiences for the prevention and mitigation of slope disasters.The research work and results of this paper are as follows.Used Fiber Bragg Grating sensing technology,designed and developed a large-range high-precision displacement sensor(referred to as FBG displacement sensor)based on U-shaped structure and lever mechanical principle,explained the sensor sensing principle,derived the theoretical relationship equation between sensor displacement and wavelength drift,and proposed the sensor temperature self-compensation technology.Used the slope surface and internal displacement monitoring information,based on the geometric analysis method and ABAQUS numerical software,we proposed and numerically verified the different displacement characteristics that occur at the surface points of the slope when the slope slides with different slip surface shapes,and then analyzed the location of the depth where the slip surface is located by combining the team's homemade FBG strain tubes to monitor the internal deformation of the slope,and finally determined the slip surface of the slope by combining the above two points.Used the indoor calibration test,the relationship between the wavelength drift value and displacement of the FBG displacement sensor was established,and the sensitivity coefficient was derived,and the reliability of the sensor was verified by the performance test.Using the FBG strain tube calibration test,the empirical equation of the wavelength change of FBG strain tube center versus displacement was obtained.Indoor slope model tests were carried out for two different slip surface conditions,namely,homogeneous soil slope and mounded slope,and the displacement was monitored in real time at several surface points of the slope using the sensors designed in this paper.The feasibility of the sliding surface determination method based on displacement information is demonstrated from the perspective of model experiments.