特殊地段公路隧道进洞技术研究

发布时间：2018-06-21 12:45

本文选题：花山隧道 + 项连山隧道　；参考：《长安大学》2014年硕士论文

【摘要】：公路隧道洞口一般位于强风化带上，围岩比较破碎，特别是下穿既有道路、陡坡等特殊地段的隧道洞口，浅埋、偏压并且覆盖层较薄，围岩成拱能力差。怎样合理选择进洞方式，在确保安全的前提下，降低工程造价，缩短工期，同时加强对围岩破坏机理的研究是特殊地段公路隧道进洞施工急需解决的。本文总结了山岭隧道洞口段主要的支护方法、机理以及开挖方法，分析了各种施工方法的优劣性及适用条件。针对项连山隧道属于浅埋、下穿二级公路的特点，采用Midas/GTS有限元分析软件，按照实际地形建立模型，采用护拱法、管棚预加固和环形开挖留核心土法、CD工法、CRD工法、双侧壁导坑法等四种施工工法开挖，进行三维数值模拟。从施工过程中二级公路的竖向变形、塑性区分布状态和规律、洞口围岩的变形、应力特征、初期支护变化规律等方面，研究项连山隧道进洞方案对二级公路及洞口围岩的影响机制，并结合经济技术比选，得出护拱法、双侧壁导坑法开挖配合管棚是项连山隧道施工的合理进洞方式。针对花山隧道属于洞口浅埋，围岩自稳能力差、陡坡进洞的特点，采用Midas/GTS有限元分析软件，按照实际地形建立模型，分别采用管棚预加固，环形开挖留核心土法、CD工法、CRD工法、双侧壁导坑法等四种施工工法开挖，进行三维数值模拟。从施工过程中陡坡段洞口围岩的变形、塑性区分布状态和发展规律、围岩应力特征、初期支护应力变化规律等方面，研究花山隧道进洞方案对陡坡洞口围岩的影响机制，并结合经济技术比选，得出管棚预加固配合双侧壁导坑法开挖是花山隧道进洞施工的合理进洞方式。本文所得结论对项连山隧道下穿二级公路端洞口、花山隧道陡坡端洞口进洞施工提供了一定的指导和技术支持，同时对类似特殊地段隧道进洞施工具体广泛的适用性。
[Abstract]:The entrance of highway tunnel is generally located in the strong weathering zone, the surrounding rock is relatively broken, especially through the tunnel entrance of the existing road, steep slope and other special sections of the tunnel, shallow buried, partial pressure and thin overburden, the arched ability of surrounding rock is poor. How to choose the way of entering the tunnel reasonably, under the premise of ensuring the safety, reducing the project cost and shortening the time limit, and strengthening the study on the failure mechanism of surrounding rock are urgently needed to be solved in the construction of the tunnel entry in the special section. In this paper, the main supporting methods, mechanism and excavation methods of the entrance section of the Shanling tunnel are summarized, and the advantages and disadvantages of various construction methods and their applicable conditions are analyzed. In view of the characteristics of Xianglianshan Tunnel which belongs to shallow buried and underpass second class highway, Midas / GTS finite element analysis software is used to establish the model according to the actual terrain, and the method of protecting arch, pre-reinforcement of pipe shed and circular excavation and retaining core earth method are used to construct CRD method. Three-dimensional numerical simulation was carried out by excavation of four kinds of construction methods such as double side wall guide pit method. In the process of construction, the vertical deformation of the secondary highway, the distribution and law of plastic zone, the deformation of surrounding rock at the entrance of the tunnel, the characteristics of stress, the law of change of initial support, etc. This paper studies the influence mechanism of Xianglianshan tunnel entry scheme on the second class highway and surrounding rock of the tunnel mouth, and combining with economic and technical comparison, it is concluded that the reasonable tunnel entry mode is the arch protection method and the double side wall guide pit method to excavate the combined pipe shed in the Xianglianshan tunnel construction. In view of the characteristics of Huashan Tunnel which is shallow buried at the entrance of the tunnel, with poor self-stability of surrounding rock and steep slope into the tunnel, the Midas / GTS finite element analysis software is used to establish the model according to the actual terrain, respectively, the pipe sheds are pre-strengthened and the circular excavation is made with the core earth method CD method and the CRD method. Three-dimensional numerical simulation was carried out by excavation of four kinds of construction methods such as double side wall guide pit method. From the aspects of deformation, distribution and development law of plastic zone, stress characteristics of surrounding rock and the change law of initial support stress during construction, the influence mechanism of entry scheme of Huashan tunnel on surrounding rock of steep slope entrance is studied. Combined with economic and technical comparison, it is concluded that the excavation of pipe shed pre-reinforcement and double-sidewall guide pit method is a reasonable way of tunnel entry construction in Huashan Tunnel. The conclusions of this paper provide some guidance and technical support for the construction of the entrance of Xianglianshan Tunnel through the end of the second class highway and the end of the steep slope of the Huashan Tunnel. At the same time, it is widely applicable to the tunnel entry construction in similar special areas.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U455.4

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