Research On Deformation Monitoring Of Ground-based SAR In Complex Environment

With the development of society,the construction of high-rise buildings,bridges,deep foundation pits and high side slopes becomes more and more magnificent.The process will cause changes in the relationship between local loads and mechanics,and even lead to uneven deformation and disasters.If the early warning and prevention are not monitored in time,the safety of people’s lives and property will be threatened.How to carry out accurate and reliable real-time monitoring of large-scale construction projects,analyze the law of force and deformation,and ensure the safety of construction and operation has become an important topic in modern society.In view of the limitations of conventional monitoring methods,such as high precision,high spatial-temporal resolution and real-time data acquisition,this paper studies the deformation monitoring algorithm and application of ground-based SAR(GBSAR)in complex environment.The main work is as follows:(1)On the basis of fully expounding the principle and data processing flow of wavelet transform,GBSAR deformation monitoring,aiming at the problem of radar line of sight occlusion caused by the interference of construction operation in the engineering application of GBSAR,a method of interference image recognition based on wavelet transform singularity detection is proposed,which transforms the interference image recognition into gross error detection.Through the simulation experiment to simulate the typical deformation curve of the target under the condition of radar line of sight occlusion,and using different wavelet bases to detect the singularity caused by the mutation,it is concluded that the coefficients of d1 and d2 layers of db N wavelet after high-frequency reconstruction can accurately detect the GBSAR interference image.(2)The wavelet transform singularity detection method is applied to the subway high slope GBSAR deformation monitoring experiment under complex construction environment.After data processing and analysis,the singular value detection results are compared with the monitoring occlusion interference image records,the consistency rate is 0.9.The singularity detection method weakens the influence of complex environment on GBSAR monitoring.Comparing the deformation monitoring results of GBSAR high slope after the interference image is eliminated with the data collected by the total station of some characteristic points,in the long-term continuous regional deformation monitoring,the internal coincidence accuracy and stability of GBSAR monitoring is better than that of the total station.Finally,the stability of high slope during monitoring is analyzed by combining GBSAR with total station,level and crack data.(3)In this paper,the detection method of GBSAR interference image recognition is used to carry out the loading deformation monitoring experiment of solid model bridge,which accurately identifies the error image introduced by human interference,and proves the feasibility and applicability of the interference image recognition method.By comparing the monitoring results with the dial indicator data,it is concluded that the deformation error of the GBSAR from Los to vertical is related to the deformation degree of the bridge body and the elevation of radar line of sight,but the deformation monitoring results of mm level can be obtained by simple geometric projection method.(4)In order to weaken the decoherence phenomenon of GBSAR monitoring target,the PS time series processing method with large amount of data is used to improve the density of coherent points and realize high-precision continuous deformation monitoring of ground-based SAR.Taking the foundation pit monitoring of a super high-rise building under construction in Xiangtan as an example,the overall accumulated displacement and deformation curve of the GBSAR in the survey area in time series is obtained.Combined with the geological conditions and construction progress of the monitoring area,the influence law of the construction building on the stability of the foundation pit itself and surrounding buildings is summarized and analyzed,which further embodies the superiority of the GBSAR deformation monitoring technology compared with the traditional method.