管棚预支护对隧道掌子面稳定性影响的研究

发布时间：2018-02-10 20:53

本文关键词： 隧道管棚预支护力学机理监测试验掌子面稳定性　出处：《重庆大学》2015年硕士论文　论文类型：学位论文

【摘要】：管棚预支护是一种经济实用的隧道辅助工法,在浅埋暗挖隧道的开挖中发挥了重大作用。管棚预支护技术拥有加固围岩、提高隧道围岩等级及抗渗性能、提高隧道掌子面稳定性和控制地表沉降等较多优点。本文以沪昆客专贵州段背阴坡隧道工程为依托,以隧道开挖过程中管棚内力和变形以及隧道掌子面稳定性为研究对象,通过理论分析、现场试验和数值模拟等方法,对管棚预支护力学模型、管棚预支护效果及其影响因素进行了较为系统和深入的研究,并对管棚预支护的设计进行了优化。主要研究内容和成果如下:①以管棚预支护与围岩之间的相互作用关系为基础,建立了基于双参数Pasternak弹性地基梁理论的管棚预支护力学模型,提出了基于有限差分法的管棚内力的求解方法。通过对管棚作用荷载的分析,推导出管棚的扰度方程及应力、应变计算公式;建立了基于地基反力方程的隧道掌子面稳定性分析方法,并应用该方法推导了管棚预支护下隧道掌子面极限支护力的计算公式。②通过对沪昆专线贵州段背阴坡隧道的现场监测试验,获得了隧道拱顶沉降、周边收敛、地表下沉及管棚预支护的应力应变变化规律。通过数据分析,得到了管棚预支护体系在隧道开挖过程中的受力特性和作用机理。③应用有限元软件MIDAS/GTS NX,建立了背阴坡隧道在管棚预支护情况下的有限元分析模型,对比了有、无管棚预支护隧道掌子面及围岩塑性区范围、管棚内力变化及隧道净空变形规律,并将计算结果与监测试验数据进行对比,证实了在浅埋偏压隧道开挖中,管棚预支护能够很好地抑制地表沉降和拱顶下沉,提高掌子面及围岩稳定性,满足工程要求。④系统分析了钢管直径、环向净距、开挖进尺、管棚长度四种管棚预支护效果的影响因素,并通过有限元软件建立同一参数不同情况下的数值模型,计算各工况下掌子面及围岩塑性分布区,管棚内力,隧道净空变形等对掌子面稳定性有关的计算结果,得到各参数对管棚预支护效果的影响程度。最后对各参数进行优化,使管棚工法在今后的地下工程中具有更高的经济性和实效性。
[Abstract]:The pipe-shed pre-support is an economical and practical auxiliary engineering method for tunnels, which plays an important role in the excavation of shallow buried tunnels. The technology of pipe-shed pre-support has the advantages of strengthening surrounding rock, improving the grade of tunnel surrounding rock and improving the impermeability of tunnel surrounding rock. To improve the stability of tunnel face and control the surface subsidence, this paper takes the Yuyin slope tunnel project in Guizhou section of Hukunke special college as the basis, takes the inner force and deformation of pipe shed and the stability of tunnel face as the research object during the tunnel excavation. Through theoretical analysis, field test and numerical simulation, the mechanical model of pipe shed pre-support, the effect of pipe shed pre-support and its influencing factors are studied systematically and deeply. The main research contents and results are as follows: 1. Based on the interaction between pipe shed pre-support and surrounding rock, the mechanical model of pipe shed pre-support based on two-parameter Pasternak elastic foundation beam theory is established. A finite difference method is proposed to solve the internal force of the pipe shed. Through the analysis of the action load of the pipe shed, the perturbation equation and the formula of stress and strain are derived. The stability analysis method of tunnel face based on foundation reaction equation is established. By using this method, the calculation formula .2 of the limit support force of tunnel face under pipe shed pre-support is derived. 2. Through the field monitoring test of the backside slope tunnel in Guizhou section of the Shanghai-Kunming special line, the settlement of the tunnel arch roof is obtained, and the circumference converges. The variation of stress and strain of surface subsidence and pipe shed pre-support. In this paper, the mechanical characteristics and action mechanism of pipe shed pre-supporting system during tunnel excavation are obtained. 3. By using finite element software MIDAS/GTS NX, the finite element analysis model of backcover slope tunnel under the condition of pipe shed pre-support is established, and the results are compared. The range of plastic zone of tunnel face and surrounding rock, the variation of inner force in pipe shed and the law of tunnel clearance deformation without pipe shed are compared with the monitoring test data, and it is proved that in the excavation of shallow burying bias pressure tunnel, The pipe shed pre-support can restrain the ground subsidence and arch roof subsidence, improve the stability of the face and surrounding rock, and meet the engineering requirements of .4 systematic analysis of the diameter of steel pipe, circumferential net distance, excavation advance, The influence factors of pipe shed length on the effect of pipe shed pre-support are analyzed, and the numerical model of the same parameter and different conditions is established by finite element software, and the plastic distribution area of the face and surrounding rock of the pipe shed is calculated under each working condition, and the inner force of the pipe shed is calculated. The calculation results related to the stability of the face of the tunnel, such as tunnel clearance deformation, are obtained, and the influence of each parameter on the pre-support effect of the pipe shed is obtained. Finally, the parameters are optimized. The pipe-shed method is more economical and effective in the future underground engineering.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U455.7

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