破碎片麻岩三车道公路隧道施工方法研究

发布时间：2018-03-11 14:40

本文选题：三车道隧道　切入点：数值模拟　出处：《兰州交通大学》2014年硕士论文　论文类型：学位论文

【摘要】：近年来我国交通事业迅猛发展，大断面隧道如雨后春笋般迅速增长，相对应的施工问题也越来越多，，如何选择最优的施工方法是我们当前面临的首要问题，技术的进步是保证施工安全、优化设计、降低工程成本的关键因素。兰州市九州隧道是处于片麻岩地段的三车道公路隧道，最大开挖跨度15.83m,最大开挖高度10.57m。本文结合九州隧道工程，对大断面公路隧道的施工方法做进一步的研究。研究内容与方法： (1)以隧道围岩变形及支护结构力学监测为基础，采用非线性拟合方法分析九州隧道工程变化规律，并通过绘制应力及位移时程曲线，得出隧道支护结构受力的变化规律。 (2)以甘肃省兰州市九州隧道为背景，建立力学计算模型，采用midas GTS进行数值模拟，将计算结果（拱顶的沉降、净空水平位移、围岩与衬砌的受力及围岩与衬砌的内力和变形）与施工过程的实际监测数据进行分析对比，验证数值模拟的科学性，为隧道施工时的安全提供重要的技术支撑和理论保障，并为隧道设计阶段参数的优化提供了可靠的技术支撑。 (3)模拟不同的开挖方法：两台阶五步开挖、三台阶七步开挖、上台阶CD法，分析各开挖方法围岩及支护结构的变形与应力，结合各不同开挖方法的实际成本进行对比分析，利用价值工程原理优选开挖方法。研究成果： (1)实测分析得到采用三台阶七步开挖破碎片麻岩隧道随时间变化规律：观测断面周边关键点位置的位移、围岩的压力、钢拱架的应力、锚杆轴力以及衬砌应力等均出现了严重的不对称现场，主要是由于该断面埋深较浅，受到左线刷坡施工的影响较大。 (2)通过三维模拟对比分析，对于破碎片麻岩隧道，采用上台阶CD法可以减小围岩及支护结构的变形及受力，最大沉降发生在拱顶处，为1.02cm，钢拱架的最大应力发生在右拱肩处，为-72.6MPa；喷混凝土的最大压应力发生在左拱腰处，为-12.0MPa；右最大跨部位出现围岩压力最大值，其值为319.6KPa。 (3)两台阶五步开挖的成本为6407.7元/米、三台阶七步开挖的成本为7821.7元/米、上台阶CD法的成本为9012元/米；两台阶要比三台阶节省1414元/米，比上台阶CD法节省2604.3元/米，九州隧道右线全长2768，两台阶比三台阶节省391万，比CD节省721万 (4)通过分析比选，采用上台阶CD法可以有效控制围岩及支护结构的受力和变形；采用两台阶五步开挖，可以节约资金，降低工程成本。
[Abstract]:In recent years, with the rapid development of transportation in our country, the large section tunnel is growing rapidly, and the corresponding construction problems are more and more. How to choose the best construction method is the most important problem that we are facing at present. The progress of technology is the key factor to ensure construction safety, optimize design and reduce project cost. The Jiuzhou Tunnel in Lanzhou City is a three-lane highway tunnel in gneiss area with a maximum excavation span of 15.83 m and a maximum excavation height of 10.57 m. This paper makes further research on the construction method of large-section highway tunnel combined with Jiuzhou Tunnel Project. Research contents and methods:. 1) based on the monitoring of surrounding rock deformation and supporting structure mechanics, the nonlinear fitting method is used to analyze the variation law of Jiuzhou tunnel project, and by drawing the time history curve of stress and displacement, the variation law of tunnel supporting structure is obtained. Taking the Jiuzhou Tunnel of Lanzhou City, Gansu Province as the background, the mechanical calculation model is established, and the numerical simulation is carried out by midas GTS. The calculated results (the settlement of the vault, the horizontal displacement of the clearance, and the horizontal displacement of the vault) are calculated. The stress of surrounding rock and lining and the internal force and deformation of surrounding rock and lining) are analyzed and compared with the actual monitoring data of construction process, which verifies the scientific nature of numerical simulation and provides important technical support and theoretical guarantee for the safety of tunnel construction. It also provides reliable technical support for the optimization of tunnel design parameters. 3) simulating different excavation methods: two steps five steps excavation, three steps seven steps excavation, up step CD method, analyzing the deformation and stress of surrounding rock and supporting structure of each excavation method, and comparing and analyzing the actual cost of different excavation methods. Using the principle of value engineering, the optimal excavation method is selected. Research findings:. 1) the measured results show that three steps and seven steps are used to excavate broken gneiss tunnel with time: displacement of key points around observation section, pressure of surrounding rock, stress of steel arch frame, The axial force of anchor rod and the stress of lining appear serious asymmetry field, mainly because of the shallow buried depth of the section, which is greatly affected by the construction of the left line brushing slope. (2) through 3D simulation and contrast analysis, for broken gneiss tunnel, the deformation and force of surrounding rock and supporting structure can be reduced by using upper step CD method. The maximum settlement occurs at the arch top (1.02cm), and the maximum stress of steel arch frame occurs at the right arch shoulder. The maximum compressive stress of shotcrete occurs at the left arch, which is -12.0MPa, and the maximum pressure of surrounding rock appears in the right maximum span with a value of 319.6KPa. The cost of two-step five-step excavation is 6407.7 yuan / m, the cost of three-step seven-step excavation is 7821.7 yuan / m, the cost of upper step CD method is 9012 yuan / m, the cost of two steps is 1414 yuan / m less than that of three steps, and 2604.3 yuan / m compared with the upper step CD method. The full length of the right line of Jiuzhou tunnel is 2768. The two steps save 3.91 million compared with three steps, and the saving of CD 7.21 million. 4) by analyzing and selecting, using the method of upper step CD can effectively control the stress and deformation of surrounding rock and supporting structure, and adopting two-step five-step excavation can save money and reduce the project cost.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U455.4

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