利用探地雷达技术进行青藏公路与高原冻土相互影响研究

发布时间：2018-05-26 12:00

本文选题：青藏高原 + 青藏公路　；参考：《中国地质大学(北京)》2017年硕士论文

【摘要】：青藏高原作为全球纬度最低、海拔最高、面积最大的冻土区,其冻土分布范围广泛,相比于高纬度冻土,高海拔冻土厚度更薄、平均温度更高因此更加敏感,很容易受到外界因素的影响而发生改变。其发展和变化对全球的气候,区域的生态环境和人类的经济活动都会产生巨大的影响。然而随着青藏地区的经济发展,青藏公路、铁路等工程项目对高原气候造成了局部性的扰动,引起冻土退化,而冻土退化必将造成地表条件的变化,从而影响到工程项目的稳定性。相对于其他在冻土地区修筑的公路铁路,青藏地区的冻土更加敏感,青藏公路下覆的高温多年冻土的冻融造成的路基的反复冻胀和热融更加剧烈,导致路基的不均匀沉降。然而,研究青藏公路不均因沉降的原因就要综合考虑路基、季节活动层、多年冻土融化区以及多年冻土层的状态等因素。因此研究融化层的厚度问题和多年冻土层的上限问题是研究冻土对青藏公路影响的基础,研究青藏公路两侧冻土区的冻土分界面、融化层厚度和多年冻土上限等问题对研究多年冻土与青藏公路的相互影响关系有很大的意义。选定青藏公路沿线北麓河段区域进行本研究工作。本研究通过青藏公路沿途经过的北麓河研究区域,利用SIR30E探地雷达进行实地探测获得垂直于青藏公路的长测线剖面,研究了实验区整体的冻土分布情况;利用CMP数据与宽角发射数据通过速度分析获取电磁波的传播速度反演融化层厚度以及多年冻土的顶界面,并利用平行剖面建立三维数据体分析了小区域范围的多年冻土分布。研究结果表明;结合长剖面的层位与速度分析得出的速度,反算出融化层底界面为1.0-1.5m,多年冻土层上限深度为2.0-3.0m之间;北麓河地区青藏公路两侧冻土分布深度明显高于天然地表下的冻土分布深度,越靠近青藏公路冻土上界面越深,冻土退化现象明显;利用相互平行的剖面建立三维数据体获取地下层位信息:分析Y方向切片可以发现,在实验区中段20-40m距离公路120-140m的范围内存在一个多年冻土下凹;分析X方向切片可以发现在近路端多年冻土的起伏相对剧烈,随着远离公路,起伏逐渐变缓,当距离公路100m时,几乎看不到多年冻土的起伏,观察多年冻土的深度,随着距离公路原来越远,冻土上限越来越浅。
[Abstract]:The Qinghai-Xizang Plateau, as a permafrost region with the lowest latitude, the highest elevation and the largest area, has a wide range of permafrost distribution. Compared with the high latitude permafrost, the high altitude permafrost is thinner in thickness and the higher the average temperature is, so it is more sensitive. It is easy to change by external factors. Its development and change will have a great impact on the global climate, regional ecological environment and human economic activities. However, with the economic development of the Qinghai-Tibet region, the Qinghai-Tibet Highway, Railway and other engineering projects have caused local disturbances to the plateau climate and caused the degradation of the frozen soil, which will inevitably cause changes in the surface conditions. Thus affecting the stability of the project. Compared with other highway and railway construction in frozen soil area, the frozen soil in Qinghai-Tibet region is more sensitive. The repeated frost heaving and thermal thawing of roadbed caused by freezing and thawing of high temperature permafrost under Qinghai-Tibet highway lead to uneven settlement of roadbed. However, to study the uneven settlement of Qinghai-Xizang Highway, the factors such as subgrade, seasonal active layer, thawing zone of permafrost and the state of permafrost must be considered comprehensively. Therefore, studying the thickness of thawed layer and the upper limit of permafrost is the basis of studying the influence of permafrost on the Qinghai-Tibet Highway, and the frozen soil interface on both sides of the Qinghai-Tibet Highway. The thawing layer thickness and the permafrost upper limit are of great significance for the study of the interaction between permafrost and the Qinghai-Tibet Highway. The northern Piedmont region along the Qinghai-Xizang Highway is selected for this study. Through the study of the study area of the Northern Piedmont River along the Qinghai-Tibet Highway, the long line profile perpendicular to the Qinghai-Tibet Highway is obtained by using SIR30E ground penetrating radar, and the distribution of frozen soil in the whole experimental area is studied. The thickness of thawed layer and the top interface of permafrost were obtained by velocity analysis of CMP data and wide-angle emission data, and the distribution of permafrost in small area was analyzed by using parallel profile. The results show that the bottom interface of the thawed layer is 1.0-1.5m and the upper limit depth of permafrost is 2.0-3.0m, which is obtained from the analysis of the horizon and velocity of the long profile. The depth of frozen soil distribution on both sides of Qinghai-Xizang Highway is obviously higher than that under natural surface, and the interface of frozen soil near Qinghai-Tibet Highway is deeper and the degradation of frozen soil is obvious. Using parallel sections to build 3D data bodies to obtain underground information: analysis of Y direction section can find that there is a permafrost depression within the range of 20-40m distance from highway 120-140m in the middle of the experimental area; It can be found that the undulation of permafrost is relatively severe in the near end of the road by analyzing the X direction slice. With the distance from the highway, the fluctuation becomes slowly. When 100m away from the highway, the undulation of permafrost is almost invisible, and the depth of permafrost is observed. With the distance from the highway, the upper limit of frozen soil is shallower and shallower.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U416.1

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