基于SBAS-InSAR的冻土形变建模及活动层厚度反演研究

发布时间：2018-02-13 05:15

本文关键词： 冻土青藏高原短基线集技术冻土形变活动层厚度　出处：《中南大学》2014年硕士论文　论文类型：学位论文

【摘要】：冻土是地球五大圈层之一—冰冻圈的重要组成部分。在全球气候变暖的大背景下,青藏高原多年冻土呈现面积缩小、活动层厚度增大等退化趋势,这将深刻影响着寒区生态环境、水文环境、经济建设、工程建设、人民生活等。大面积、高精度的开展冻土监测对于研究全球气候变化及保障寒区人民生命财产安全具有重要意义。传统SBAS-InSAR技术虽然能够监测冻土形变,但其形变模型并不适合描述冻土形变,且如何利用InSAR技术获取冻土活动层厚度仍然是一个研究热点。基于此,本论文构建顾及气候因子影响的冻土形变模型获取冻土形变,并在此基础上发展活动层厚度反演算法。本文研究工作和贡献主要包括： (1)分析土质、地质构造活动等内因和外部气候因子对冻土形变的影响,建立顾及气候因子影响的SBAS-InSAR冻土形变模型,提取研究区域的冻土时间序列形变。研究区内天然地表下冻土年周期变形量均介于4-5.5cm之间,青藏铁路沿线、青藏公路沿线年周期形变量介于3-4cm。冻土的形变与气温、降水量呈现负相关关系,相关性分别达到了0.61、0.91。 (2)基于本文建立的冻土形变模型,利用SBAS-InSAR技术获取冻土形变,假设冻土夏季沉降全部由活动层中冰融化成水引起冻土层体积收缩造成,简化工程上采用的冻土融沉量分层计算模型,逆运算得到冻土融化深度,并进一步推算研究区多年冻土上限,2007年8月多年冻土上限约为0～223cm,均值处在102～153cm之间,2010年8月约0～364cm,均值处在108～158cm之间。 (3)宁中盆地多年冻土上限整体上从地势较低的盆地中央向海拔较高的盆地边缘逐渐减小,2010年8月冻土上限均比2007年8月有所增加,并可推算出该区域冻土上限以每年1～2cm的速度在增加,预计百年后多年冻土活动层厚度将增加0.9～1.8m。这将对研究区域的生态环境、工程建设产生影响,对青藏铁路和青藏公路的安全运行也构成一定威胁。
[Abstract]:Permafrost is one of the five major layers of the earth, which is an important part of the cryosphere. Under the background of global warming, the permafrost of the Qinghai-Xizang Plateau tends to decrease in area and increase in thickness of active layer. This will have a profound impact on the ecological environment, hydrological environment, economic construction, engineering construction, people's daily life and so on in cold regions. High precision monitoring of frozen soil is of great significance to the study of global climate change and the safety of people's lives and property in cold regions. Although the traditional SBAS-InSAR technology can monitor the frozen soil deformation, its deformation model is not suitable to describe the frozen soil deformation, and how to obtain the thickness of the frozen soil active layer by using the InSAR technique is still a research hotspot. In this thesis, a frozen soil deformation model considering the influence of climate factors is constructed to obtain the frozen soil deformation, and on this basis, the inversion algorithm of active layer thickness is developed. The research work and contributions in this paper are as follows:. 1) analyzing the influence of internal and external climatic factors, such as soil quality, geological tectonic activity, on frozen soil deformation, and establishing the SBAS-InSAR frozen soil deformation model, which takes into account the influence of climate factors. The time series deformation of frozen soil was extracted from the study area. The annual periodic deformation of frozen soil in the study area was between 4-5.5 cm, along the Qinghai-Tibet Railway and along the Qinghai-Xizang Highway between 3-4cm.The deformation and temperature of permafrost, There was a negative correlation between precipitation and precipitation, respectively. (2) based on the model of frozen soil deformation established in this paper, the SBAS-InSAR technique is used to obtain the frozen soil deformation. It is assumed that the summer settlement of frozen soil is caused by the volume shrinkage of frozen soil caused by the melting of ice in the active layer. The thawing depth of frozen soil is obtained by inverse calculation by simplifying the layered calculation model of thawing settlement of frozen soil. Furthermore, the permafrost upper limit in the study area is estimated to be 0 ~ 223cm in August 2007, with a mean value of 102103cm, and a mean value of 108m ~ 158cm in August 2010. (3) the permafrost upper limit of Ningzhong basin decreases gradually from the center of the basin with lower topography to the basin margin with higher elevation on the whole, and the upper permafrost limit in August 2010 is higher than that in August 2007. It can also be deduced that the upper limit of frozen soil in this area is increasing at the speed of 1 ~ 2 cm per year, and it is expected that the thickness of the active layer of permafrost will increase by 0.9 ~ 1.8 m after 100 years. This will have an impact on the ecological environment and engineering construction of the study area. It also poses a certain threat to the safe operation of the Qinghai-Tibet Railway and the Qinghai-Tibet Highway.
【学位授予单位】：中南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P642.14

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