Development Of Slope Deformation Monitoring System Based On Optical Fiber And Electromagnetic Sensing Technology

Landslide is a vary dangerous global geological disaster.With the rapid development of sensing technology in recent years,optical fiber grating,piezoelectric,MEMS and other advanced photoelectric sensors have gradually demonstrated the advantages of high precision,low power consumption and easy to form sensing network in the monitoring field.In this paper,based on fiber Bragg grating and electromagnetic sensing technology,a variety of new landslide inclination-measuring instruments that can be used in landslide deformation monitoring have been developed independently.The whole process of the indoor landslide model under the action of overload is monitored by the method of indoor landslide model test.Based on the numerical method,the stability analysis model of indoor landslide is established by combining the displacement monitoring data of an indoor sensors with the safety coefficient.Based on the field long-term displacement monitoring data,the classic early warning model of Saito landslide was modified.This paper mainly does the following work:(1)Fiber Bragg grating(FBG)was combined with organic polymer material to make a fiber Bragg grating inclinometer.The theoretical formula was derived by using conjugate beam method.The effectiveness of this sensor was verified by building a indoor calibration device with a special steel frame and displacement meter.A piecewise optical fiber grating inclinometer structure based on an equal strain beam is proposed to further reduce the cumulative error.(2)In order to solve the problem of large deformation monitoring in the middle and late stages of landslides,new magnetic sensor inclinometers based on magnetostrictive materials and Hall elements were proposed and designed,and magnetic field test platforms for magnetostrictive materials and Hall elements were designed and prepared.The formula between the FBG wavelength value and the tilt angle of the magnetostrictive displacement sensor is obtained.The empirical formula between the change of the magnetic field value of the Hall element and the tilt angle of the Hall displacement sensor is obtained and a comprehensive performance analysis is performed.(3)The loading system and slope model in the overload landslide experiment were designed,and the selection and layout of new sensors were proposed.Three new types of displacement sensors were combined with micro-electromechanical systems(MEMS)to form a quasi-distributed monitoring network.The deformation information in the whole process is collected,and the shape and position of the slope slip surface are determined by experimental data.(4)Combined with the finite element analysis software,the landslide test process under overload is compared and verified,and a real-time analysis method of slope stability based on deep displacement monitoring data is proposed.The long-term monitoring data of the Shuichang Iron Mine in the previous literature was selected to modify the traditional Saito model,and compared with the traditional Saito method by regression extrapolation.The results show that the modified Saito model can predict more accurately Landslide time.