Application Research Of Fast-GBSAR In Dam Deformation Monitoring In Plateau Deep Cutting Area

Along with the development of China’s comprehensive national strength,the construction of large-scale hydro-junction projects has achieved remarkable results,and the health monitoring of the high dam reservoir in plateau deep cutting area is even more important,which is of great significance for supporting the social and economic development and the people’s livelihood security.Up to now,41 high dams have been built in China with a height of more than 200 meters,of which,the height of Jinping first-level hyperbolic arch dam located on Yalong River in Western Sichuan Plateau is 305 meters,ranking first in China.The security operation of the high dam reservoir is directly related to the property security of the downstream people and the economic benefits of the country.Therefore,in order to improve the capability of managing the safety risks of the dam,it is urgent to initiate a study of deformation monitoring techniques for high dam reservoirs.Ground-Based Synthetic Aperture Radar(GB-SAR),which has powerful deformation monitoring capability and has developed rapidly in the deformation monitoring of large-scale hydraulic facilities,provides a high-precision,non-contact,non-destructive,stable and real-time safety monitoring system for dam deformation monitoring.However,there are still some urgent problems to be solved in the deformation monitoring application of GB-SAR,such as the inconsistency between GB-SAR coordinate system and traditional measurement equipment coordinate system,the atmospheric influence during the monitoring process,which affect the accuracy of GB-SAR monitoring results and multi-source monitoring methods.In this paper,based on the Fast Ground Based Synthetic Aperture Radar(Fast-GBSAR)system of Metasensing Company of the Netherlands,the application of ground radar system in dam deformation monitoring in the deep cutting area was studied,mainly focusing on the fusion of high-precision two-dimensional deformation map of GB-SAR and DEM data by three-dimensional laser scanner,time series analysis technology based on candidate points of permanent Scatterers,and Fast-GBSAR system atmospheric phase correction.The experimental data of dam were discussed to provide scientific basis and theoretical support for deformation monitoring of GB-SAR in the high dam reservoir.The main research contents and innovations points of this paper are summarized as follows:(1)Based on the research of conventional deformation monitoring technology and spaceborne SAR deformation monitoring technology,this paper develops the process of the new dam deformation monitoring technology(GB-SAR)in the deep cutting area,optimizes the monitoring process,and summarizes the advantages of GB-SAR in dam monitoring.This technology overcomes the problems of image incoherence,long data acquisition period and satellite incident angle limitation in the application of spaceborne SAR technology in deformation monitoring in plateau deep cutting area,which provides high precision,stability and real-time dynamic deformation monitoring for safe operation of high dam reservoir in western Sichuan plateau.(2)In order to solve the problem of difficulty in interpretation of deformation monitoring images,a method of fusion of three-dimensional laser scan data and GB-SAR data was proposed,which analyze and interpret the monitoring targets more comprehensively.On this basis,the application of permanent Scatterers technique in atmospheric phase correction was studied for the influence of irregular atmospheric disturbance during the monitoring of GB-SAR,and the global permanent Scatterers candidate point and filtering method were proposed to correct the monitoring data and improve the accuracy of deformation monitoring.(3)Taking Jinping dam in plateau deep cutting area as monitoring object,through in-depth analysis of the state and stability of dam during monitoring period,we propose that the tide in the reservoir has a periodic effect on the horizontal deformation of the dam and the dam is in a stable state.It indicates that GB-SAR technology provides reliable assurance for dam deformation monitoring.