本文選題：青藏高原 + 青藏公路　； 參考：《中國地質(zhì)大學(北京)》2017年碩士論文

【摘要】：青藏高原作為全球緯度最低、海拔最高、面積最大的凍土區(qū),其凍土分布范圍廣泛,相比于高緯度凍土,高海拔凍土厚度更薄、平均溫度更高因此更加敏感,很容易受到外界因素的影響而發(fā)生改變。其發(fā)展和變化對全球的氣候,區(qū)域的生態(tài)環(huán)境和人類的經(jīng)濟活動都會產(chǎn)生巨大的影響。然而隨著青藏地區(qū)的經(jīng)濟發(fā)展,青藏公路、鐵路等工程項目對高原氣候造成了局部性的擾動,引起凍土退化,而凍土退化必將造成地表條件的變化,從而影響到工程項目的穩(wěn)定性。相對于其他在凍土地區(qū)修筑的公路鐵路,青藏地區(qū)的凍土更加敏感,青藏公路下覆的高溫多年凍土的凍融造成的路基的反復凍脹和熱融更加劇烈,導致路基的不均勻沉降。然而,研究青藏公路不均因沉降的原因就要綜合考慮路基、季節(jié)活動層、多年凍土融化區(qū)以及多年凍土層的狀態(tài)等因素。因此研究融化層的厚度問題和多年凍土層的上限問題是研究凍土對青藏公路影響的基礎(chǔ),研究青藏公路兩側(cè)凍土區(qū)的凍土分界面、融化層厚度和多年凍土上限等問題對研究多年凍土與青藏公路的相互影響關(guān)系有很大的意義。選定青藏公路沿線北麓河段區(qū)域進行本研究工作。本研究通過青藏公路沿途經(jīng)過的北麓河研究區(qū)域,利用SIR30E探地雷達進行實地探測獲得垂直于青藏公路的長測線剖面,研究了實驗區(qū)整體的凍土分布情況;利用CMP數(shù)據(jù)與寬角發(fā)射數(shù)據(jù)通過速度分析獲取電磁波的傳播速度反演融化層厚度以及多年凍土的頂界面,并利用平行剖面建立三維數(shù)據(jù)體分析了小區(qū)域范圍的多年凍土分布。研究結(jié)果表明;結(jié)合長剖面的層位與速度分析得出的速度,反算出融化層底界面為1.0-1.5m,多年凍土層上限深度為2.0-3.0m之間;北麓河地區(qū)青藏公路兩側(cè)凍土分布深度明顯高于天然地表下的凍土分布深度,越靠近青藏公路凍土上界面越深,凍土退化現(xiàn)象明顯;利用相互平行的剖面建立三維數(shù)據(jù)體獲取地下層位信息:分析Y方向切片可以發(fā)現(xiàn),在實驗區(qū)中段20-40m距離公路120-140m的范圍內(nèi)存在一個多年凍土下凹;分析X方向切片可以發(fā)現(xiàn)在近路端多年凍土的起伏相對劇烈,隨著遠離公路,起伏逐漸變緩,當距離公路100m時,幾乎看不到多年凍土的起伏,觀察多年凍土的深度,隨著距離公路原來越遠,凍土上限越來越淺。
[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.
【學位授予單位】：中國地質(zhì)大學(北京)
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：U416.1

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