浅埋大断面软弱围岩隧道进洞技术研究

发布时间：2019-05-16 01:16

【摘要】：随着我国社会经济的快速发展,高速公路的建设越来越多,尤其在西部山区修建隧道,地形、地质条件复杂,隧道施工难度大。洞口段一直被视为隧道的咽喉,与其他段相比具有埋深浅,围岩一般风化严重且破碎的特点。再加上高速公路隧道开挖断面大,隧道进洞施工过程中,极易引起洞口坍塌、大变形等工程事故。因此对浅埋大断面软弱围岩隧道的进洞技术研究就显得十分重要。本文以某新建双向六车道隧道为依托,采用理论分析、数值模拟以及现场监测的方法对隧道进洞技术进行研究。主要研究内容如下:(1)根据国内外已有研究成果,总结浅埋大断面软弱围岩的特性及变形的影响因素,同时对隧道进洞技术的超前支护、隧道开挖方法以及支护方法进行总结和分析。(2)以依托工程洞口段为研究对象,采用有限元法建立环形开挖留核心土法、CD法、CRD法、双侧壁导坑法四种不同施工方法结合超前管棚支护的进洞开挖模型,分析不同施工方法开挖过程中对洞口围岩变形、围岩应力、初期支护结构应力的影响。数值模拟结果表明:双侧壁导坑法完成开挖后,引起地表沉降、隧道拱顶下沉及周边收敛最大值分别为:9.02mm、22.77mm、13.51mm,比其他工法变形更小且未超过规范允许值;同时围岩应力初期支护结构应力均小于其他工法。因此,采用双侧壁导坑法结合管棚超前支护作为进洞方案。(3)对依托工程采用本文建议的进洞方案,进行了三维数值模拟,并结合洞口段YK159+360、YK159+370断面监控量测的拱顶下沉、周边收敛以及地表沉降结果进行对比,结果表明:实测值与模拟值存在一定的误差,但围岩的变形规律基本一致,验证了隧道所建议的进洞方案可行。
[Abstract]:With the rapid development of social economy in our country, the construction of expressway is more and more, especially in the western mountainous area, the terrain and geological conditions are complex, and the tunnel construction is difficult. The entrance section has always been regarded as the throat of the tunnel, which has the characteristics of shallow buried depth and serious weathered and broken surrounding rock compared with other sections. In addition, the excavation section of expressway tunnel is large, and it is easy to cause the collapse of tunnel entrance, large deformation and other engineering accidents in the process of tunnel entrance construction. Therefore, it is very important to study the tunnel entry technology of shallow buried large section weak surrounding rock tunnel. In this paper, based on a new two-way six-lane tunnel, the tunnel entry technology is studied by means of theoretical analysis, numerical simulation and field monitoring. The main research contents are as follows: (1) according to the existing research results at home and abroad, the characteristics of shallow buried large section weak surrounding rock and the influencing factors of deformation are summarized, and the advanced support of tunnel entry technology is also summarized. The tunnel excavation method and support method are summarized and analyzed. (2) taking the tunnel entrance section as the research object, the ring excavation core soil method, CD method and CRD method are established by finite element method. The effects of four different construction methods on the deformation of surrounding rock, the stress of surrounding rock and the stress of initial supporting structure in the excavation process of different construction methods are analyzed by combining the excavation model of advance pipe shed support with four different construction methods. The numerical simulation results show that the surface subsidence is caused by the bilateral wall pit guide method, and the maximum values of tunnel arch roof subsidence and peripheral convergence are 9.02 mm, 22.77 mm and 13.51 mm, respectively, which are smaller than those of other construction methods and do not exceed the allowable values of the code. At the same time, the stress of supporting structure in the initial stage of surrounding rock stress is lower than that of other construction methods. Therefore, the double side wall pit guide method combined with pipe shed advance support is used as the tunnel entry scheme. (3) the three dimensional numerical simulation is carried out by using the hole entry scheme suggested in this paper, and combined with YK159 360 of the entrance section of the tunnel, The results of arch roof subsidence, peripheral convergence and surface subsidence measured by YK159 370 section are compared. the results show that there is a certain error between the measured value and the simulated value, but the deformation law of surrounding rock is basically the same. It is verified that the proposed tunnel entry scheme is feasible.
【学位授予单位】：西安工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U455.4

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