浅埋暗挖法隧道上穿既有盾构隧道的变形控制研究

发布时间：2018-03-28 18:27

本文选题：浅埋暗挖法　切入点：既有盾构隧道　出处：《北京交通大学》2015年博士论文

【摘要】：随着城市人口的急速膨胀,城市地下空间的集约式利用使得地下结构之间相互的影响问题日益突出。本文在总结新建工程穿越既有城市轨道交通工程经验和研究成果的基础上,紧密结合北京CBD地区银泰至航华大断面地下过街人行通道上穿地铁10号线工程,通过理论分析、数值计算、室内模型试验和现场实时监测的方法,系统研究了浅埋暗挖隧道上穿既有盾构隧道的变形规律及受力情况,并提出了相应的变形控制措施,主要工作及研究成果如下： (1)通过三维数值模拟计算和室内模型试验,得到既有盾构隧道变形的总体规律,预测得到既有隧道的上浮值。随着上部隧道的开挖,既有隧道结构的变形经历了先上浮后回落,速率先大后小,并逐渐趋于稳定的过程。通过室内模型试验,发现在既有隧道和上方隧道交汇断面处,土压力减小值要明显大于交汇断面两侧处的土压力减小值,且上下侧土压力值差也较大,说明交汇断面上浮较大,验证了计算结论。据此初步确定了合理的隧道开挖方案和土层加固方案。 (2)基于正交试验理论构建正交试验,研究表明覆跨比、夹土层厚度对隧道上浮值具有显著影响。结合实际工程特点,提出了此正交试验应以拱顶上浮值、拱底上浮值、隧道径向相对位移、隧道竖向相对位移4项作为评价指标,试验结果方差分析和极差分析表明：夹土层厚度是上穿施工时既有隧道变形程度的最重要影响因素,为合理的注浆设计提供了依据。 (3)建立了上穿既有隧道施工的解析模型,推导得出了上部卸载情况下既有盾构隧道横向变形曲率的计算公式,并分析了实际工程中既有隧道的横截面安全性。建立了上部卸载情况下既有隧道纵向受力模型,分别推导了单弹簧模型和双弹簧模型下上部卸载引起的既有隧道挠度、转角、弯矩、剪力,结合实际工程分析了双弹簧模型的适用性,研究表明单弹簧模型比双弹簧模型计算得到的隧道上浮值要大。 (4)通过现场监测研究发现：大断面通道上穿施工引起的既有盾构隧道结构变形总体以上浮为主、结构自身变形较小,隧道结构竖向位移、水平收敛及道床结构竖向位移的变化规律一致,均经历了快速上升区、急速回落区、波动下降区及后期波动稳定区4个阶段。在工程地质与水文地质条件、夹土层厚度基本相同条件下,上穿西线隧道的通道覆跨比0.75、上穿东线隧道的通道覆跨比0.95的情况下，，而通道施工引起的既有隧道的竖向变形量东线2.3mm要明显的小于西线隧道4.1mm,可见覆跨比越大隧道的上浮值越小,正交试验分析结果与现场实测结果一致。 (5)基于对既有盾构隧道的工前状况检测,掌握了既有隧道的状态,依托数值分析的预测,利用变位分配原理对新建隧道施工过程进行控制,成功的控制了既有隧道的上浮值。通过加强注浆和超前支护,减小了既有隧道的变形速率,也减小了隧道所受弯矩。研究表明数值预测、分部变位控制并加强现场量测在穿越既有线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.

【学位授予单位】：北京交通大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：U455.4

【参考文献】