【摘要】：隨著城市交通量大量增長，地鐵成為解決交通堵塞的一個有效的手段，目前我國已經(jīng)有大量城市開通地鐵或者正在進行地鐵建設(shè)了。同時，城市的地面發(fā)展也是快速發(fā)展，不可避免的出現(xiàn)大量在地鐵隧道上建設(shè)的基坑工程。上方的基坑和下方的既有隧道相互影響，基坑開挖必然對既有下方地鐵盾構(gòu)隧道造成影響，將會影響到地鐵的安全運營。目前，關(guān)于基坑開挖對既有下方地鐵盾構(gòu)隧道變形的影響研究還不夠完善，本文采用有限元軟件Midas/GTS進行數(shù)值模擬的方法，研究基坑開挖對下方隧道造成變形的規(guī)律。本文主要做了以下工作： （1）介紹了本文的研究背景，總結(jié)了關(guān)于基坑開挖對下臥既有盾構(gòu)隧道變形影響的研究現(xiàn)狀，提出了本文的研究方法和解決的問題。 （2）分析了基坑開挖引起土體變形的機理，總結(jié)歸納了基坑開挖引起的周圍土壓力計算方法、基坑隆起的回彈量計算方法、殘余應(yīng)力的計算方法以及基坑變形的影響因素；總結(jié)了基于彈性地基梁理論的基坑開挖對下臥隧道的變形計算方法，，給出了下臥隧道的附加應(yīng)力、豎向變形、擾度、彎矩、轉(zhuǎn)角以及剪力的計算方法和解析解。 （3）通過Midas/GTS的數(shù)值模擬分析，對基坑開挖過程造成隧道變形影響進行模擬分析，分別對各施工階段、不同基坑尺寸、不同基坑與隧道相對位置、不同基坑開挖方法、不同工程地質(zhì)條件對隧道的變形影響進行分析。分析結(jié)果表明：隧道的位移以豎向位移為主，變形最大處出現(xiàn)在基坑開挖至底部時；基坑寬度、垂直距離、軸線相對距離對隧道變形影響顯著，呈線性關(guān)系；垂直距離、軸線相對距離對隧道水平位移影響不大；基坑沿隧道縱向的長度對隧道變形影響不大；基坑的支護和支撐結(jié)構(gòu)能減小隧道的變形；基坑分塊開挖能減小隧道的最大豎向位移，在底板澆筑前，能縮短隧道最大變形的暴露時間；工程地質(zhì)條件對隧道變形有顯著影響，地質(zhì)條件越差，隧道產(chǎn)生的變形越大。 （4）總結(jié)歸納了在既有下臥隧道的基坑開挖工程保護措施和工程監(jiān)測技術(shù)。
[Abstract]:With the rapid growth of urban traffic, subway has become an effective means to solve traffic jams. At present, a large number of cities in China have opened the subway or are carrying out subway construction. At the same time, the ground development of the city is also rapid development, inevitably there are a large number of foundation pit construction on the subway tunnel. The foundation pit above and the existing tunnel below affect each other, and the excavation of foundation pit will inevitably affect the shield tunnel under the existing subway, which will affect the safe operation of the subway. At present, the research on the influence of foundation pit excavation on the deformation of shield tunnel under existing subway is not perfect. In this paper, the method of finite element software Midas / GTS is used to simulate the deformation of underground tunnel caused by excavation of foundation pit. The main work of this paper is as follows: (1) the research background of this paper is introduced, and the research status of the influence of foundation pit excavation on the deformation of existing shield tunnel is summarized. The research methods and the problems solved in this paper are put forward. (2) the mechanism of soil deformation caused by foundation pit excavation is analyzed, and the calculation method of surrounding earth pressure caused by foundation pit excavation and the calculation method of springback amount of foundation pit uplift are summarized. The calculation method of residual stress and the influencing factors of foundation pit deformation are summarized, and the calculation method of foundation pit excavation deformation to underside tunnel based on elastic foundation beam theory is summarized, and the additional stress, vertical deformation, disturbance, bending moment of subhorizontal tunnel are given. (3) through the numerical simulation analysis of Midas / GTS, the influence of tunnel deformation caused by excavation process is simulated and analyzed. Different relative positions of foundation pit and tunnel, different excavation methods and different engineering geological conditions are used to analyze the influence of tunnel deformation. The results show that the displacement of the tunnel is mainly vertical displacement, and the maximum deformation occurs when the foundation pit is excavated to the bottom, the width, vertical distance and relative distance of axis have significant influence on the tunnel deformation, and the vertical distance is linear. The relative distance of axis has little effect on the horizontal displacement of the tunnel; the longitudinal length of the foundation pit has little effect on the tunnel deformation; the supporting and supporting structure of the foundation pit can reduce the deformation of the tunnel; and the maximum vertical displacement of the tunnel can be reduced by the block excavation of the foundation pit. Before the bottom slab is cast, the exposure time of the maximum deformation of the tunnel can be shortened, and the engineering geological conditions have a significant effect on the tunnel deformation, and the worse the geological conditions are, The deformation caused by the tunnel is greater. (4) the protection measures and engineering monitoring techniques of foundation pit excavation in the existing underside tunnel are summarized.
【學位授予單位】：華南理工大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：U452.11;U231

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