地基SAR永久散射体选取及形变探测大气影响试验研究

发布时间：2019-05-20 01:26

【摘要】：地表形变而引发的各种地质灾害不仅严重威胁人们的生命财产安全,也给国家带来了极大的经济损失。自然环境变化和人类活动等影响,均可使地表不稳定而产生形变,从而威胁人工建筑物、大坝水库等设施的安全。因此,有必要对这些形变进行快速、高精度实时监测,并分析其形变机理,以达到对形变危险进行预警的目的。传统形变测量方法成熟、精度较高,但观测点稀疏,很难提供大面积地表连续形变信息,且耗费大量人力财力,还威胁观测人员人身安全。近年,新发展起来的地基合成孔径雷达干涉测量技术,不仅具有星载SAR的全天候、全天时等观测优点,还能获取高时空分辨率和高精度SAR数据影像,且设站灵活,在形变监测领域中具有广阔的应用前景。本文在阐述地基SAR基本原理的基础上,开展了一系列形变监测试验研究,主要工作如下:首先,对快速地基SAR的形变监测可靠性进行试验研究。试验中,利用快速地基SAR系统和全站仪在同一时间段对同一目标进行监测,通过调节带有百分尺的角反射器来控制形变量,表明快速地基SAR系统的监测结果与全站仪测量结果相吻合。其次,提出了一种改进的基于平均相干系数、振幅离差指数、估计信噪比、位移精度指数的多重阈值地基SAR PS点选取方法,有效提高了所选PS点质量。对比分析了振幅离差阈值法、平均相干系数法和改进的新方法的PS点选取结果,经过实地现场验证,得出改进方法的PS选取质量优于单一阈值法(振幅离差阈值法或平均相干系数法)所得的结果。最后,PS点方法大气校正模型构建与大气校正试验。并对监测结果进行改正。利用改进的PS点方法对月湖桥和边坡试验区中的PS点提取。月湖桥试验中通过PS点选取了PSC稳定点,利用全局PSC点进行大气校正,通过对比分析提取的9个PS点改正前后的形变曲线,说明全局PSC点大气校正方法在此试验中取得了较好的改正结果。边坡试验中通过人工选取PS稳定点构建大气校正网,提取其中9个目标点改正前后的形变时间序列图进行对比,分析得出在此试验中利用构建的大气校正网进行改正有效提高了测量结果精度。
[Abstract]:All kinds of geological disasters caused by surface deformation not only seriously threaten the safety of people's lives and property, but also bring great economic losses to the country. The influence of natural environment change and human activity can make the surface unstable and cause deformation, which threatens the safety of artificial buildings, dams and reservoirs. Therefore, it is necessary to monitor these deformation quickly and accurately in real time, and analyze their deformation mechanism in order to achieve the purpose of early warning of deformation danger. The traditional deformation measurement method is mature and accurate, but the observation points are sparse, so it is difficult to provide large area continuous surface deformation information, and consumes a lot of human and financial resources, and also threatens the personal safety of observers. In recent years, the newly developed ground-based synthetic aperture radar interferometric technology not only has the advantages of all-weather and all-weather observation of space-borne SAR, but also can obtain high spatial-temporal resolution and high precision SAR data images, and the station is flexible. It has a broad application prospect in the field of deformation monitoring. On the basis of expounding the basic principle of foundation SAR, a series of deformation monitoring experiments are carried out in this paper. the main work is as follows: firstly, the reliability of deformation monitoring of rapid foundation SAR is studied. In the experiment, the fast foundation SAR system and the total station are used to monitor the same target at the same time, and the shape variables are controlled by adjusting the angular reflector with a percentile. The results show that the monitoring results of the fast foundation SAR system are in good agreement with those of the total station. Secondly, an improved multi-threshold foundation SAR PS point selection method based on average coherence coefficient, amplitude deviation index, estimation signal-to-noise ratio (SNR) and displacement accuracy index is proposed, which effectively improves the quality of the selected PS point. The PS point selection results of amplitude deviation threshold method, average coherence coefficient method and improved new method are compared and analyzed, which are verified in the field. It is concluded that the PS selection quality of the improved method is better than that of the single threshold method (amplitude deviation threshold method or average coherence coefficient method). Finally, the atmospheric correction model of PS point method is constructed and the atmospheric correction experiment is carried out. The monitoring results are corrected. The improved PS point method is used to extract PS points from Yuehu Bridge and slope test area. In the Yuehu Bridge test, the PSC stable point is selected by PS point, and the atmospheric correction is carried out by using the global PSC point. The deformation curves of 9 PS points extracted before and after correction are compared and analyzed. It is shown that the global PSC point atmospheric correction method has achieved good correction results in this experiment. In the slope test, the atmospheric correction network is constructed by manually selecting PS stable points, and the deformation time series diagrams of nine target points before and after correction are extracted and compared. It is concluded that the accuracy of the measurement results is effectively improved by using the constructed atmospheric correction network in this experiment.
【学位授予单位】：湖南科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU196

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