| China is rich in mineral resources,with reserves and production of various minerals ranking among the top in the world,and a sound mining system with complete varieties.Therefore,it is necessary to discharge and store a large amount of tailings every year.According to statistics,China’s mining industry discharges up to 300 million tons of tailings annually,with a cumulative tailings storage capacity of nearly 20 billion tons.Most of the tailings are stored in the form of tailings ponds.Tailings pond is one of the three major projects of the mine,and it is also a hazard of man-made debris flow with high potential energy.Once a dam breach accident occurs,it will seriously damage the environment and threaten the safety of downstream people’s lives and property.Therefore,it is particularly important to monitor the deformation of the tailings pond itself and its surrounding surface.At present,the existing research mostly uses the level,total station,GNSS(Global Navigation Satellite System)and sensors to obtain the deformation of some points on the tailings pond,which is difficult to achieve efficient,high-precision and refined deformation monitoring of the tailings pond.And InSAR(Interferometric Synthetic Aperture Radar)technology has the ability to monitor all day,all weather,strong penetration,and large-scale,and temporal InSAR technology has made significant progress.However,the traditional InSAR technology has the problem of insufficient monitoring point density and poor monitoring effect in non-urban areas.The DS-InSAR(Distributed Scatterers InSAR)technology has improved the coherence of these areas,increased the density of monitoring points and improved the monitoring effect through homogeneous point identification and phase optimization.Due to the different reflections of radar electromagnetic waves by different ground objects,single polarization can only reflect the scattering information of some ground objects and fusing different polarization information will help to obtain more surface information.In response to the above situation,this article conducted in-depth research on the DSInSAR method.Comparing different homogeneous point selection algorithms and phase optimization algorithms.At the same time,deformation monitoring research was conducted on the Brumadinho tailings pond in Brazil and the Kafang tailings pond in Yunnan as experimental areas,and the dynamic deformation laws of the region were revealed in conjunction with local precipitation data.The main research work and achievements are as follows:(1)The necessity of large-scale and high-precision deformation monitoring of tailings ponds was analyzed,and the development of InSAR technology and research status at home and abroad were introduced.Elaborated on the basic principles,methods,and disadvantages of D-InSAR(Differential InSAR)technology.In response to the above shortcomings,the advantages of temporal InSAR technology were introduced in detail.Pointed out the feasibility,reliability,and advantages of using polarized SAR data for deformation monitoring,laying a foundation for subsequent theoretical research and application.(2)Research a DS-InSAR method based on the FaSHPS(FastSHPSelection)algorithm and eigenvalue decomposition method.A comparative analysis was conducted on different single polarization homogeneous point recognition methods.The experimental results showed that the FaSHPS algorithm can effectively overcome the problem of low efficiency in traditional homogeneous point recognition methods,reduce Class II errors,and demonstrate the efficiency of the FaSHPS algorithm in largescale homogeneous point recognition.On this basis,single polarization distributed targets were selected based on homogeneous point thresholds,and phase optimization was performed using eigenvalue decomposition method.The interferograms before and after optimization were compared and analyzed,verifying the effectiveness and feasibility of eigenvalue decomposition.(3)Research the multipolarized DS-InSAR method incorporating polarization information.The advantages of HTCI(Hypothesis Test of Confidence Interval)over other homogeneous point recognition methods were compared and analyzed using Monte Carlo simulation experiments.Based on the HTCI algorithm,a polarization homogeneous point recognition method was studied.The classification of pixels based on homogeneous point threshold and amplitude dispersion index improves the classification accuracy of persistent scatterers and polarized distributed targets.Optimize PS(Persistent Scatterer)based on amplitude dispersion index.In order to suppress the impact of polarized distributed target noise,MMSE(Minimum Mean Square Error)filtering is performed first,and then optimization is performed according to the coherence index to improve the phase quality.(4)The Brumadinho tailings pond in Brazil and the Kafang tailings pond in Yunnan were selected as the research areas,and deformation monitoring was conducted on two tailings ponds at different time periods using DS-InSAR and multipolar DSInSAR methods.The results show that the method proposed in this thesis has high consistency with other methods.Within each monitoring time period,the two methods can effectively increase the density of monitoring points in tailings ponds,obtain more detailed deformation information of tailings ponds,and analyze the variation characteristics of tailings ponds over time.The correlation between deformation information and local precipitation data indicates that the deformation of the tailings pond is influenced by local precipitation.the Brumadinho tailings pond in Brazil has a significant acceleration trend in deformation before the dam failure.However,the deformation of the Kafang tailings pond during the research period is relatively stable due to its small deformation variables.The research method in this article can provide reference for efficient,high-precision,and refined deformation monitoring of other tailings ponds.There are 47 pictures,8 tables and 159 references. |
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