| The research on the early warning and monitoring of natural disasters of landslides has always been a major issue related to the production and life of our nationals.The accuracy and real-time nature of landslide monitoring and early warning methods have always been the focus of this research field.If these problems cannot be solved well,it will affect the process of landslide monitoring and early warning research,resulting in serious loss of national property and even adversely affecting life safety.Therefore,monitoring and early warning research on landslide disasters is very necessary.Early warning and monitoring research on landslides mainly relied on methods such as geodetic technology,displacement sensors,and measuring robots,all of which have their own drawbacks and limitations.Therefore,in order to improve the accuracy and real-time performance of early warning and monitoring of landslides,this paper applies distributed Brillouin optical time domain reflectometry(BOTDR)to the early warning and monitoring of landslides by detecting the frequency shift of the sensing fiber.Improve the accuracy and real-time performance of landslide monitoring and early warning research.Research content: Use the optical characteristics of the sensing fiber to monitor the location and intensity of strain during landslides.Because the deformation process of landslides is very complicated,the cost of real-time monitoring and early warning of mountain slopes is very high,and it is difficult to observe the state of various regions of the mountain during the entire landslide process.If a single monitoring program is used,it will be difficult to accurately understand the global slope change status,so the dual-parameter system that combines BOTDR technology and phase-sensitive OTDR technology is used for landslide early warning.For the surface layer of the landslide-prone mountain,the optical fiber is arranged in a horizontal and vertical orthogonal combination,and the optical signal in the optical fiber is demodulated and analyzed.According to the analysis results,complete the safety monitoring of the location area and determine whether a landslide occurs;in order to simulate the accumulation of sediment and crushed rock in the process of landslides,a1000×400×400 mm(length×width×height)double-plate stress monitoring experiment was made The model integrates BOTDR into the early warning and monitoring of landslides.A composite displacement detection device was designed to detect and analyze the frequency shift of the optical fiber during the landslide process by means of simulation experiments;the distributed optical fiber monitoring method was used to characterize the entire process of the landslide with the change of the optical fiber's own parameters.The concept of the average degree of displacement of the displacement is used to visually represent the average displacement of the slope surface of a certain optical fiber monitoring area.Then the experimental data is sorted out and studied,and it is concluded that there is a correlation between the displacement value and the deformation data.The innovation of this paper is to apply the distributed Brillouin scattered light time-domain reflectance technology to the landslide monitoring experiment.Through the relationship between the frequency shift and strain of the sensing optical fiber,it can characterize the overburden rock layer on the slope surface during the landslide process.The deformation.Through the displacement measurement and data homogenization of the overlying soil on the surface of the mountain slope,the sliding process of the mountain surface during the landslide process is visually displayed and analyzed.The concept of the average change degree of the surface displacement of the landslide is put forward and the mathematical expression is established,and the sliding state of the surface of the mountain slope in the landslide process at each location area and the average displacement of the entire measuring point are represented by this.In order to simulate the sediment accumulation process in the landslide,the slope double-plate stress monitoring model was made,the BOTDR monitoring system was applied to the three-dimensional model experiment of the landslide,and the displacement measurement experiment and frequency shift were carried out by simulating the landslide and sediment accumulation process Monitor the experiment.Design a fiber optic fixed-point monitoring instrument(fiber time domain calibration device)to locate the sampling point position in the experiment,and accurately locate the point where the strain occurs in the sensing fiber to determine the location coordinate of the landslide;use the fiber frequency shift threshold alarm system To make a judgment on the amount of change in the frequency shift of the optical signal in the optical fiber,and divide it into an early warning level. |
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