本文選題：淺埋暗挖法　切入點：既有盾構(gòu)隧道　出處：《北京交通大學》2015年博士論文

【摘要】：隨著城市人口的急速膨脹,城市地下空間的集約式利用使得地下結(jié)構(gòu)之間相互的影響問題日益突出。本文在總結(jié)新建工程穿越既有城市軌道交通工程經(jīng)驗和研究成果的基礎(chǔ)上,緊密結(jié)合北京CBD地區(qū)銀泰至航華大斷面地下過街人行通道上穿地鐵10號線工程,通過理論分析、數(shù)值計算、室內(nèi)模型試驗和現(xiàn)場實時監(jiān)測的方法,系統(tǒng)研究了淺埋暗挖隧道上穿既有盾構(gòu)隧道的變形規(guī)律及受力情況,并提出了相應的變形控制措施,主要工作及研究成果如下： (1)通過三維數(shù)值模擬計算和室內(nèi)模型試驗,得到既有盾構(gòu)隧道變形的總體規(guī)律,預測得到既有隧道的上浮值。隨著上部隧道的開挖,既有隧道結(jié)構(gòu)的變形經(jīng)歷了先上浮后回落,速率先大后小,并逐漸趨于穩(wěn)定的過程。通過室內(nèi)模型試驗,發(fā)現(xiàn)在既有隧道和上方隧道交匯斷面處,土壓力減小值要明顯大于交匯斷面兩側(cè)處的土壓力減小值,且上下側(cè)土壓力值差也較大,說明交匯斷面上浮較大,驗證了計算結(jié)論。據(jù)此初步確定了合理的隧道開挖方案和土層加固方案。 (2)基于正交試驗理論構(gòu)建正交試驗,研究表明覆跨比、夾土層厚度對隧道上浮值具有顯著影響。結(jié)合實際工程特點,提出了此正交試驗應以拱頂上浮值、拱底上浮值、隧道徑向相對位移、隧道豎向相對位移4項作為評價指標,試驗結(jié)果方差分析和極差分析表明：夾土層厚度是上穿施工時既有隧道變形程度的最重要影響因素,為合理的注漿設計提供了依據(jù)。 (3)建立了上穿既有隧道施工的解析模型,推導得出了上部卸載情況下既有盾構(gòu)隧道橫向變形曲率的計算公式,并分析了實際工程中既有隧道的橫截面安全性。建立了上部卸載情況下既有隧道縱向受力模型,分別推導了單彈簧模型和雙彈簧模型下上部卸載引起的既有隧道撓度、轉(zhuǎn)角、彎矩、剪力,結(jié)合實際工程分析了雙彈簧模型的適用性,研究表明單彈簧模型比雙彈簧模型計算得到的隧道上浮值要大。 (4)通過現(xiàn)場監(jiān)測研究發(fā)現(xiàn)：大斷面通道上穿施工引起的既有盾構(gòu)隧道結(jié)構(gòu)變形總體以上浮為主、結(jié)構(gòu)自身變形較小,隧道結(jié)構(gòu)豎向位移、水平收斂及道床結(jié)構(gòu)豎向位移的變化規(guī)律一致,均經(jīng)歷了快速上升區(qū)、急速回落區(qū)、波動下降區(qū)及后期波動穩(wěn)定區(qū)4個階段。在工程地質(zhì)與水文地質(zhì)條件、夾土層厚度基本相同條件下,上穿西線隧道的通道覆跨比0.75、上穿東線隧道的通道覆跨比0.95的情況下，，而通道施工引起的既有隧道的豎向變形量東線2.3mm要明顯的小于西線隧道4.1mm,可見覆跨比越大隧道的上浮值越小,正交試驗分析結(jié)果與現(xiàn)場實測結(jié)果一致。 (5)基于對既有盾構(gòu)隧道的工前狀況檢測,掌握了既有隧道的狀態(tài),依托數(shù)值分析的預測,利用變位分配原理對新建隧道施工過程進行控制,成功的控制了既有隧道的上浮值。通過加強注漿和超前支護,減小了既有隧道的變形速率,也減小了隧道所受彎矩。研究表明數(shù)值預測、分部變位控制并加強現(xiàn)場量測在穿越既有線工程中是非常必要和有效的。
[Abstract]:With the rapid expansion of city population, city intensive utilization of underground space makes the mutual influence between the increasingly prominent problems of underground structure. Based on the summary of the new project through the existing city rail traffic engineering experience and research results, combined with large section in Beijing District of CBD to Yintai HANGHUA underground walkways wear on the subway 10 line project, through theoretical analysis, numerical calculation method of indoor model test and field monitoring system, research the deformation rule of shallow buried tunnel through existing shield tunnel force and deformation, and puts forward the corresponding control measures, the main work and research results are as follows:
(1) by three-dimensional numerical simulation and indoor model test, obtained as well as the general rules of shield tunnel deformation, prediction of tunnel excavation of tunnel with upper float value. The deformation of the existing tunnel structure experienced a floating rate after the fall, the first after the small, and gradually tends to be stable. Through indoor model test, found in the existing tunnel and above the tunnel junction section, earth pressure decreases to be significantly greater than the soil pressure at both sides of the intersection section decreases, and the lower value of earth pressure difference, that the intersection section floating large calculation proves the conclusion. According to preliminary determine the reasonable scheme and soil excavation the tunnel reinforcement scheme.
(2) to construct orthogonal orthogonal test based on the theory of research shows that the cross cover ratio, clip thickness has a significant impact on the floating value. Combined with the actual tunnel engineering characteristics, puts forward the orthogonal test should be based on the floating vault, arch bottom float value, tunnel radial displacement, the vertical displacement of the tunnel 4 as the evaluation index. The test results show that the variance analysis and range: clip soil thickness wear on construction are the most important factors influencing the degree of tunnel deformation, provide the basis for the reasonable design of grouting.
(3) was established through existing analytical model of tunnel construction, deduces the calculation formula of both lateral deformation curvature of shield tunnel upper unloading situation, and analysis of the cross section of the existing tunnel safety in practical engineering is established. Both the longitudinal force model of the upper part of the tunnel unloading conditions, respectively. Is the single spring model and double spring model is caused by unloading of the existing tunnel deflection, rotation, bending moment, shear force, combined with the applicability of the double spring model analysis of practical engineering, research shows that tunnel floating single spring model than double spring model calculated value should be large.
(4) through the study of field monitoring found that large section channel wear caused by construction of both the overall deformation of shield tunnel structure floats above the main structure, its deformation is small, the vertical displacement of tunnel structure, consistent with the variation of horizontal convergence and vertical displacement of the track structure, have experienced rapid rise, rapid decline, 4 stage fluctuation drop zone and post stability area. In the engineering geological and hydrogeological conditions, with basic soil thickness under the same conditions, in West tunnel cross cover more than 0.75, wear on the East tunnel cross cover ratio of 0.95, while the vertical channel caused by the construction of the tunnel deformation of the East 2.3mm was significantly smaller than the West tunnel 4.1mm, visible cover span is smaller than the tunnel floating value analysis of orthogonal test results consistent with the measured results.
(5) the detection of existing shield tunnel work before based on the situation, the existing tunnel, relying on the prediction of numerical analysis, control of the new tunnel construction process by using the principle of variable assignment, successful control of the existing tunnel floating value. By strengthening grouting and super before supporting, reduced the rate of deformation of existing tunnel, reduces the tunnel bending moment. The results show that the numerical prediction, segment displacement control and strengthen field measurement in cross the existing engineering is very necessary and effective.

【學位授予單位】：北京交通大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：U455.4

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