【摘要】：由于城市地質條件的限制及地下空間的綜合開發(fā)利用,在地下工程中不可避免地產(chǎn)生近距離大直徑泥水平衡盾構雙線隧道施工。如果新建隧道與已建隧道的間距較小,新建隧道的挖掘必然會改變已建隧道周圍土體的應力分布狀況,進而對已建隧道襯砌的受力及變形產(chǎn)生影響,同時也會影響新建隧道的安全施工。本文以在建的上海虹梅南路隧道工程中閔行區(qū)段存在長距離超大直徑極小距離雙線泥水平衡盾構掘進為工程背景,主要應用ABAQUS有限元數(shù)值分析軟件建立三維彈塑性模型分析雙線隧道施工相互影響,重點是在研究超大直徑極小間距泥水平衡式盾構施工的相互影響的基礎上,提出減少新建隧道對已建隧道的不利影響的有效措施,保證隧道施工過程中的安全,并能夠為今后相關的隧道施工提供一定的參考借鑒。本文主要工作和研究成果如下:1.結合上海土質的特殊性及現(xiàn)場單線隧道監(jiān)測數(shù)據(jù),分析研究超大直徑盾構單線施工對周圍土層的擾動情況;同時從理論上探討超大直徑在軟粘土中施工引起的地表沉降機理,采用修正的鏡像位移法可以有效的預測地表沉降規(guī)律。2.依托實際工程,通過采用有限元數(shù)值分析軟件ABAQUS建立三維模型對雙線隧道施工進行數(shù)值模擬,研究在不同土層、不同埋深及不同間距下雙線平行隧道地表變形機理。模擬結果顯示:土層彈性模量越大地表沉降及周圍土層擾動越小;其次,雙線隧道間距對先建隧道穩(wěn)定性影響較大,間距越小隧道間的土層擾動越大;此外盾構掘進埋深對周圍土層擾動影響復雜,在不同的埋深下沉降呈現(xiàn)的規(guī)律不同,如當開挖面正上方土質較軟時,隧道軸線上方土層相對周圍土層有“隆起”趨勢。3.同樣借助于有限元分析軟件分析在極小間距雙線隧道中心線處設置不同隔離樁間距、不同隔離樁樁長等保護措施,研究雙線平行隧道襯砌變形機理。結果表明設置隔離樁可以有效地減小雙線隧道地表和襯砌拱頂最大沉降值以及襯砌環(huán)彎矩值;其次,隔離樁間距越密相互影響越小,但是隨著隔離樁加密襯砌整體水平方向偏移值增大;同時,隔離樁樁長對雙線隧道施工影響比較大,樁長越長相互影響越小。4.結合部分現(xiàn)場監(jiān)測數(shù)據(jù)分析后建隧道對先建隧道的影響,數(shù)值模擬值與實測值結果相近,可以用于盾構推進過程中土層擾動的預測分析。
[Abstract]:Due to the limitation of urban geological conditions and the comprehensive development and utilization of underground space, it is inevitable to produce a large-diameter shield tunnel in the underground engineering. If the distance between the new tunnel and the built tunnel is small, the excavation of the new tunnel will inevitably change the stress distribution of the soil around the built tunnel, and then affect the stress and deformation of the lining of the built tunnel. At the same time, it will also affect the safety of the new tunnel construction. In this paper, the engineering background is the existence of long distance super-large diameter extremely small distance double-line mud water balanced shield tunneling in the section of Minhang District in the construction of Hongmenan Road Tunnel project in Shanghai. In this paper, ABAQUS finite element numerical analysis software is used to establish a three-dimensional elastic-plastic model to analyze the interaction between the construction of double-line tunnels. The emphasis is on the study of the interaction between the super-large diameter and minimal spacing mud-water balanced shield construction. The effective measures to reduce the adverse effects of the new tunnel on the existing tunnel are put forward to ensure the safety in the course of tunnel construction and to provide some reference for the relevant tunnel construction in the future. The main work and research results are as follows: 1. Based on the particularity of soil quality in Shanghai and the monitoring data of single-line tunnel in site, the disturbance to the surrounding soil layer caused by the single-line construction of super-large diameter shield tunneling is analyzed and studied. At the same time, the mechanism of surface subsidence caused by the construction of super-large diameter in soft clay is discussed theoretically. The modified mirror displacement method can effectively predict the law of surface subsidence. 2. Based on the actual engineering, the 3D model of double-track tunnel construction is established by using finite element software ABAQUS, and the surface deformation mechanism of double-line parallel tunnel under different soil layers, different buried depth and different spacing is studied. The simulation results show that the larger the elastic modulus of soil layer is, the smaller the surface settlement is and the smaller the surrounding soil layer disturbance is. Secondly, the interval between two tunnels has a greater influence on the stability of the first built tunnel, and the smaller the interval is, the greater the disturbance of soil layer is. In addition, the influence of shield tunneling depth on the disturbance of surrounding soil layer is complex, and the law of settlement under different burial depth is different. For example, when the soil above the excavated surface is relatively soft, the soil layer above the tunnel axis has a tendency of "uplift" relative to the surrounding soil layer. With the help of the finite element analysis software, the mechanism of lining deformation of double-line parallel tunnel is studied by means of the protection measures such as different separation pile spacing and different isolation pile length at the center line of double-line tunnel with minimal spacing. The results show that the maximum settlement value and the moment value of the lining ring can be effectively reduced by setting the isolation pile. Secondly, the closer the separation pile spacing is, the smaller the mutual influence is, but with the increase of the overall horizontal deviation value of the isolated pile, the length of the isolated pile has a greater influence on the construction of the double-line tunnel, and the longer the pile length is, the smaller the mutual influence is. 4. Combined with some field monitoring data, the influence of the post-built tunnel on the pre-built tunnel is analyzed. The numerical simulation results are similar to the measured values, which can be used to predict and analyze the soil disturbance during the shield tunneling process.
【學位授予單位】：上海理工大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：U455.43

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本文編號：2425544