【作者】 张微；

【导师】 陈汉林； 杨树锋； 肖安成；

【作者基本信息】 浙江大学 ， 构造地质学， 2008， 博士

【摘要】 雷达差分干涉测量(D-InSAR:Differential Interferometric Synthetic ApertureRadar)成像技术是20世界末兴起的一种新型空间对地观测技术,是精密地形测绘、微小地表形变测量的重要手段之一。现今地壳形变资料是地壳最新构造运动的直观表征,也反映了区域现今地壳运动特征。本文运用D-InSAR技术对杭州地区近期的地壳形变特征进行了监测,并结合区域地质资料、地球物理资料、水文地质资料以及钻孔资料等对地壳形变机理进行了深入的探讨。本论文主要取得以下研究成果:1、研究了D-InSAR地表形变监测的基本原理和技术流程,并结合杭州地区实际条件,提出了“三轨法”为杭州地区最优的地表形变监测模式。2、对SAR图像斑点噪声形成机理、数学模型进行了深入的研究,提出了改进的小波软阈值法SAR图像去噪方法,并根据平滑指数及边缘保持指数证明该方法的综合性能优于中值滤波、Lee滤波、小波硬阈值和小波软阈值等传统方法。3、分析了相位解缠方法的原理及数学模型,对当前七种相位解缠算法进行实现和优选,分析了各自的适用条件和优缺点,优选出其中最适合杭州地区的基于统计耗费网络流的相位解缠算法,并对解缠效果和计算效率进行了评价;4、提出了提升小波变换融合方法,并与IHS变换等方法进行了比较。同时结合边缘增强等方法对杭州地区断裂的遥感信息进行提取,并结合测年技术、重力及航磁异常处理及野外验证等手段对断裂的活动性进行了分析。认为杭州地区存在着第四纪活动断裂,但全新世晚期以来活动的可能性不大。5、获取了杭州部分地区1997～2000年的地壳形变图。形变整体上呈面状分布,分成了明显的三块区域,分别是以河山、新市为中心的东北平原形变区Ⅰ、以半山、彭埠为中心的中部平原形变区Ⅱ和棣溪北部形变区Ⅲ,其中形变区Ⅰ的范围最广,形变最强烈,最大累计形变量达4.41cm。同时,形变区呈现明显的扇形,并有向四周扩散的趋势。形变区内部及边缘未见明显的线性构造,说明与断裂关联性不大。6、研究了杭州地区地壳形变的区域构造背景、第四纪沉积序列以及地下水发育特征,并对地壳形变的控制因素和机理进行了研究。认为杭州地区的地壳形变不受断层所控制,而且受构造因素影响很小,长期过度地开采地下水是杭州地区大规模地壳形变的最主要原因。同时绘制了塘栖-乔司第四系综合柱状对比图和蒋村-下沙等3条地质剖面,认为杭州地区的地壳形变量与第四系地层厚度呈现明显的负相关性。同时证明了杭州地区地壳形变主要发生在土质松软的粘土层,砂砾石层则贡献有限;利用彭埠、杭州灯泡厂、良渚及沈家的钻孔资料证明了在同等条件下全新统粘土层对形变的影响大于上更新统粘土层;良渚-西兴剖面证明了在高压条件下,砂砾石层也会表现出较为高压缩性并导致杭州城区发生较强烈的形变。初步结果表明,D-InSAR技术用于杭州地区地壳形变监测还是可行的。然而其应用和推广还需作进一步的研究和完善,在具体的应用中还有很多瓶颈问题未得到很好的解决,比如斑点抑制问题、时间去相关问题、相位解缠算法的改进等。更多还原

【Abstract】 Differential interferometric synthetic aperture radar (D-InSAR) imaging technology was emerging at the end of the 20th century. It uses the information of the phase of two SAR images to extract height information and brings a revolution for geodesy. It has the advantages of synthetic aperture radar (SAR), such as penetrating the cloudy layer or the barrier, carrying on all-weather work all day and all night, wide mapping area, real-time imaging and high flexibility etc. These can’t be get through optical method.Present crustal deformation information is intuitive characteristics of tectonic movement of the crust, and also reflects the regional characteristics of the crustal movement. The current characteristics of crustal deformation of Hangzhou area was monitored by the D-InSAR technology and the crustal deformation mechanism was discussed deeply combined with regional geological data, geophysical data, hydrogeology and drilling data etc. The paper falls into the following parts:1. The basic theories and methods of D-InSAR technology are studied and propose the "three-pass" method as the best monitoring model of Hangzhou area.2. Make a deep research on the formation mechanism and mathematical models of the speckles of SAR images, propose a new method of noise removal of SAR image based on improved wavelet soft-thresholding method, and in accordance with smoothness index and edge preservation index prove that the comprehensive performance of this method is better than other traditional filters such as median filter, Frost filter, Lee filter, wavelet hard-thresholding and soft-thresholding.3. Analysize the theory and methodology of phase unwrapping, demonstrate and compare the current seven popular phase unwrapping algorithms, analysize their advantages and disadvantages, select statistical-cost network-flow algorithm as the most suitable algorithm used in Hangzhou area and evaluate its effectiveness and efficiency.4. Propose a new image fusion method based on lifting wavelet transformation and carry on visual interpretation and quantitative evaluation with IHS transform, PCA transform, Brovey transform and so on. Extract the information of the faults in Hangzhou area by means of edge enhancement, directional enhancement, high-pass filter, texture analysis etc. and collect gravity and areomagnetic anomalies data, shallow artificial seismic exploration data, borehole data and dating data etc. to validate the interpreted results. The results show that the faults of Hangzhou area have been active since the Quaternary, but the possibility seems less since the late Pleistocene.5. Get the crustal deformation map of Hangzhou area between 1997 and 2000. the deformation shows the characteristic of area and divides into three relative obvious regions. At the same time, the subsidence areas show sector distribution and diffusion obviously. There is no linear structure in the inner and edge of the deformed zone, which shows that the deformation has less association with the faults.5. Make a careful research on the crustal deformation mechanism of Hangzhou area combined with regional structural background, Quaternary sedimentary succession and characteristics of ground water. Conclude that it is not the major faults of Hangzhou area but long time groundwater exploitation that control the crustal deformation of Hangzhou area. At the same time, draw isopach, contour and three-dimensional strata map of Hangzhou area and prove that the thickness of Holocence is the main factors. In addition, the unit subsidence of clay layer is far larger than sand and gravel layer in low pressure condition and the subsidence was mainly concentrated in the aquifer, less consolidation or compressible consolidation of the thick clay layer.The preliminary results show that using D-InSAR technology for monitoring the ground deformation of Hangzhou area is relatively satisfied. However, monitoring the ground deformation of eastern cities of China needs further research and improvement and there are many urgent problems to solve in specific applications, for example, despeckling, time decorrelation, baseline decorrelation and the improvement of phase unwrapping algorithms and so on.更多还原