Research On Monitoring Technology Of Deep Large Displacement Of Landslide Based On Magnetic Positioning

Landslide is a common type of geological disasters in China.Its occurrence frequency is high and its destructive power is large.Monitoring and early warning is an important measure to deal with landslide geological disasters.The deep displacement of the landslide directly reflects the internal deformation of the landslide body,so the deep displacement of the landslide is an important part of monitoring and early warning.However,the existing monitoring method is difficult to complete the continuous monitoring of the deep displacement of the landslide in the case of large displacement of the landslide.With the deepening of the research of magnetic positioning technology,the scope of its application is more and more wide.Based on the shortcomings of the deep displacement monitoring technology of landslide,we propose a method of applying magnetic positioning technology to the deep displacement monitoring of landslide.The main research contents and conclusions drawn in this paper are as follows:In order to solve the problem that the deep displacement of the landslide is difficult to monitor,a magnetic measurement scheme for the deep displacement of the landslide is proposed.The specific method is as follows: the permanent magnet is buried under the sliding belt,and the magnetic sensor is installed above the sliding belt to measure the relative displacement of the sliding body.In order to eliminate the influence of geomagnetism and environmental magnetic field,an absolute difference method and a relative difference method are proposed.Through theoretical derivation and experimental verification,the scheme of measuring the magnetic field gradient around the target magnetic pole and solving the magnetic space position by relative difference method is finally selected.Assuming that the target magnetic pole is a magnetic dipole,the relationship between the magnetic field gradient and the spatial position is derived,and the correctness of the theoretical relationship is proved by verification experiments.Since the target magnetic pole is equivalent to a magnetic dipole,the theoretical formula is derived based on the calculation formula of the magnetic dipole model,but the magnetic dipole model is not applicable when the target magnetic pole is close to the magnetic sensor..In order to explore the applicable range of the magnetic dipole model,we propose a mathematical integral model and an improved magnetic dipole model for the magnetic field calculation of the target magnetic pole,and combine the relevant theories to derive the spatial magnetic field calculation formula of the two models.By selecting thespatial location,three models are used to calculate separately in MATLAB,and the calculation results are plotted.The results show that the three models are effective for the calculation of the magnetic field,but as the distance between the target magnetic pole and the magnetic sensor decreases,the error of the magnetic dipole model increases,when the distance is less than 2.5 times the maximum size of the target magnetic pole.The magnetic dipole model is not applicable.Combined with the accuracy requirements of magnetic positioning technology in deep displacement monitoring of landslides,we define the error analysis function.The calculation results show that the applicable distance of the magnetic dipole model should be greater than 1.2m,and the applicable distance of the modified magnetic dipole model should be greater than 0.6m.Based on the deformation characteristics of the landslide body,the mapping relationship between the displacement of the sliding body and the magnetic induction intensity at different inclination angles of the sliding surface is simulated.The calculation formula of the magnetic induction intensity and displacement of the magnetic sensor in different directions with the inclination of the landslide body along different sliding planes is derived.The landslide body displacement and magnetic induction intensity curve are obtained by MATLAB,and the variation of the magnetic induction intensity with the displacement is established.The mapping relationship between displacement and magnetic induction.Further verification experiments prove the correctness of the theoretical proof of the magnetic induction intensity with displacement.A method of comprehensively utilizing the magnetic induction intensity component to solve the displacement is proposed.According to the relationship between the magnetic induction intensity and the variation rate of the magnetic induction intensity with displacement,the displacement solution function of the three-segment displacement is constructed,and the applicable range of the displacement solution function is discussed.The results show that in the range of the whole magnetic positioning,the displacement of the landslide body is divided into three sections using different analytical solutions,which can solve the displacement value of the higher precision landslide body.