软质片岩隧道大变形控制技术研究

发布时间：2018-05-26 03:10

本文选题：软质片岩 + 蠕变　；参考：《华东交通大学》2014年硕士论文

【摘要】：随着国家基础建设不断发展，越来越多的公路、铁路向山区延伸，为了缩短里程和保护沿线自然环境，隧道便成为其主要的设计形式之一。由于地质条件的复杂性，使得现有的隧道工程技术尚不能完全解决工程中所遇问题，例如高地应力、仰拱隆起及软岩大变形等问题。目前，软岩大变形规律已经成为软岩隧道建设中研究的热点问题，在软岩隧道工程施工过程中控制围岩大变形往往是软岩隧道修建成功的关键。由于软岩隧道围岩变形特征的复杂性，使得软岩隧道大变形控制技术仍然处于争议和探索阶段。本文以某软质片岩隧道为工程依托，对软质片岩隧道围岩变形规律及其大变形控制技术进行系统的分析。全文的主要研究内容和结论有：（1）在分析软质片岩的岩性、工程力学特性及软质片岩受力变形特点的基础上，研究软质片岩隧道围岩大变形影响因素及其大变形特征。（2）根据前人的研究发现，软岩具有明显的流变特性，且其流变主要表现为蠕变变形；本文在分析了软岩的蠕变变形规律和本构模型的基础上，结合该隧道软质片岩围岩的变形规律，发现Burgers蠕变本构模型较为符合软质片岩的变形特性。（3）鉴于FLAC3D数值模拟软件在岩土工程上的应用及其在大变形分析上的优势，本文采用FLAC3D软件对软质片岩隧道进行数值模拟；由于软质片岩隧道结构面和节理裂隙发育，加上施工扰动作用及遇水软化等特点，将所选取的模拟区段围岩简化为各向同性材料。（4）在对所选取的五种开挖工况分别进行模拟后发现：等台阶（5.0m）长度下二台阶法和三台阶法开挖对围岩的变形和应力影响较小；超短（2.5m）台阶开挖，，能有效减小围岩的应力和变形；预留核心土能有效控制掌子面和拱顶的变形，增强掌子面的稳定性，但其对拱顶部位的塑性区影响较大。（5）对超前小导管模拟发现：超前支护能使拱顶部位形成一个承载拱，有效的控制拱顶的变形；而在超前小导管施工中改变小导管的倾角虽对围岩的稳定性起到一定的作用，但其效果并不明显。对系统锚杆的模拟发现：锚杆的长度对于其在软岩中的作用是非常明显的，选择适当长度的锚杆能起到经济高效的效果。（6）蠕变作用是解释软岩隧道围岩与支护结构相互作用的重要理论，本文从蠕变理论着手，并通过现场隧道围岩和不同支护构件的长期受力变形监测，初步分析了支护结构初期的变形受力特点及其受岩体作用下的长期稳定状态。
[Abstract]:With the continuous development of national infrastructure, more and more highways and railways extend to mountainous areas. In order to shorten mileage and protect the natural environment along the road, tunnel becomes one of its main design forms. Due to the complexity of geological conditions, the existing tunnel engineering technology can not completely solve the problems encountered in the engineering, such as high ground stress, inverted arch uplift and large deformation of soft rock, etc. At present, the law of large deformation of soft rock has become a hot issue in the construction of soft rock tunnel. Controlling the large deformation of surrounding rock in the construction of soft rock tunnel is the key to the success of soft rock tunnel construction. Due to the complexity of surrounding rock deformation characteristics of soft rock tunnel, the large deformation control technology of soft rock tunnel is still in the stage of controversy and exploration. Based on a soft schist tunnel, the deformation law of surrounding rock and its large deformation control technology in soft schist tunnel are systematically analyzed in this paper. The main contents and conclusions of this paper are as follows: 1) based on the analysis of the lithology, engineering mechanical properties and deformation characteristics of soft schist, the factors affecting the large deformation of surrounding rock in soft schist tunnel and the characteristics of large deformation are studied. 2) based on the previous studies, it is found that soft rock has obvious rheological characteristics, and its rheology is mainly characterized by creep deformation. In this paper, the creep deformation law and constitutive model of soft rock are analyzed. According to the deformation law of soft schist rock surrounding rock in this tunnel, it is found that the Burgers creep constitutive model accords with the deformation characteristics of soft schist rock. 3) in view of the application of FLAC3D numerical simulation software in geotechnical engineering and its advantage in large deformation analysis, the soft schist tunnel is numerically simulated by FLAC3D software, because of the development of structural plane and joint fracture of soft schist tunnel, Combined with the characteristics of construction disturbance and water softening, the selected surrounding rock of the simulated section is simplified as isotropic material. 4) after simulating the five kinds of excavation conditions, it is found that two step method and three step method excavation have little influence on the deformation and stress of surrounding rock under equal step length (5.0 m), and ultra-short excavation of 2.5 m) step excavation can effectively reduce the stress and deformation of surrounding rock. The reserved core soil can effectively control the deformation of palm surface and dome and enhance the stability of metacarpal surface, but it has a great influence on the plastic zone of the crown. 5) it is found that the advance support can form a bearing arch at the top of the arch, and control the deformation of the arch effectively, while changing the inclination of the small pipe in the construction of the leading small conduit plays a certain role in the stability of the surrounding rock. But its effect is not obvious. It is found that the length of the bolt is very obvious to the soft rock, and the choice of the appropriate length of the bolt can play an economic and efficient effect. (6) creep is an important theory to explain the interaction between surrounding rock and supporting structure in soft rock tunnel. The deformation and stress characteristics of the supporting structure at the initial stage and the long-term stable state under the action of the rock mass are preliminarily analyzed.
【学位授予单位】：华东交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U455.49

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