挤压性炭质千枚岩隧道模型试验及围岩变形特征研究

发布时间：2018-03-11 02:24

本文选题：挤压性高地应力　切入点：炭质千枚岩　出处：《兰州交通大学》2015年硕士论文　论文类型：学位论文

【摘要】：隧道围岩的大变形问题在挤压性软岩隧道工程建设中普遍存在。因隧道围岩的过大变形直接引起的初期支护破坏、围岩侵入限界甚至坍塌等灾害事故时有发生。因此挤压性软岩隧道施工中如何对围岩大变形进行有效的控制一直是隧道建设中的重点和难点,深入研究隧道施工过程中围岩的变形特征和规律是得到围岩大变形控制技术的基础。为了更深入了解挤压性高地应力软岩隧道台阶法施工中的围岩变形特征,借鉴和传承国内外现有研究成果,结合兰渝铁路两水隧道中大范围存在的炭质千枚岩地质特征,懫用模型试验模拟和数值计算相结合的方法,对台阶法开挖施工中的隧道围岩变形及应力变化特征等方面进行了深入研究,开展的相关工作及相关结果如下:(1)基于正交试验设计方法,将重度、黏聚力、内摩擦角和变形模量作为目标参数,用黄土、石英砂、水泥、石膏和纯净水为组料,研制了一种炭质千枚岩相似材料,能够较好地反映炭质千枚岩的基本物理力学特征。(2)设计了一整套模型试验设备,可用于研究挤压性高地应力软岩隧道施工中围岩变形、应力变化特征。设备包括试验台架、加载系统及测量系统,其特点是加载灵活、应力状态稳定、精确度高、经济性好。(3)基于现有研究成果和工程经验,设计了两种围岩等效支护结构。以薄铁板为支护材料的刚度等效支护,用以模拟较强的支护结构作用下围岩的变形情况;以铁丝网为支护材料的变形等效支护,用以模拟较弱的支护作用下围岩的变形情况,还可以在一定程度上体现整个施工过程中围岩变形情况。(4)将围岩总变形量分为三部分进行分析,反映出隧道施工过程中围岩变形的时空效应。挤压性高地应力条件下,软弱围岩开挖中的后效变形所占比例最小,先行变形和初始变形占总变形2/3以上。(5)对比不同支护强度下围岩的变形情况,分析了支护强度对围岩变形的影响。在挤压性高地应力条件下应允许软岩发生适度的变形,可避免拱部围岩产生加载效应,使支护结构更好的与围岩协调工作。(6)研究了不同支护强度下围岩的应力重分布情况,结果表明过大的支护强度会使挤压性高地应力隧道拱顶围岩产生较大的应力集中。(7)运用FLAC3D数值计算软件对隧道的台阶法分步开挖施工过程进行了模拟,对模型试验开挖过程中的围岩变形、应力变化进行了验证和拓展,得到了中间监测断面中任意位置围岩的变形、应力变化情况。(8)总结论文所做的全部工作和主要成果,并就论文的不足在相似材料、支护方式、开挖方法等方面给出了进一步的研究建议。
[Abstract]:The problem of large deformation of surrounding rock in tunnel is common in the construction of soft rock tunnel. Therefore, how to effectively control the large deformation of surrounding rock in the construction of soft rock tunnel is always the key and difficult point in tunnel construction. Deeply studying the deformation characteristics and law of surrounding rock during tunnel construction is the basis of the large deformation control technology of surrounding rock. In order to understand the deformation characteristics of surrounding rock in the construction of soft rock tunnel with high in-situ stress, the deformation characteristics of surrounding rock in the construction of soft rock tunnel with high in-situ stress are studied. Referring to and inheriting the existing research results at home and abroad, combined with the geological characteristics of carbonaceous phyllite in the Lan-Yu railway Liangshui tunnel, the method of combining model test simulation with numerical calculation is used. In this paper, the deformation and stress change characteristics of surrounding rock in tunnel excavation by step method are studied in depth. The related work and related results are as follows: 1) based on orthogonal test design method, the weight and cohesion of the surrounding rock are calculated. A carbonaceous phyllite similar material was developed using loess, quartz sand, cement, gypsum and purified water as the target parameters, such as the angle of internal friction and the modulus of deformation. A set of model test equipment is designed, which can be used to study the deformation and stress variation of surrounding rock in the construction of soft rock tunnel with high in-situ stress. Loading system and measuring system, which are characterized by flexible loading, stable stress state, high precision, good economy, etc.) based on existing research results and engineering experience, Two kinds of wall rock equivalent support structures are designed. The stiffness equivalent support with thin iron plate is used to simulate the deformation of surrounding rock under the strong support structure, and the deformation equivalent support with wire mesh as the supporting material. In order to simulate the deformation of surrounding rock under the weak support, and to some extent reflect the deformation of surrounding rock in the whole construction process, the total deformation of surrounding rock can be divided into three parts to analyze. It reflects the space-time effect of surrounding rock deformation during tunnel construction. Under the condition of high compressive stress, the proportion of post-effect deformation in excavation of soft surrounding rock is the smallest. Compared with the deformation of surrounding rock under different supporting strength, the influence of supporting strength on the deformation of surrounding rock is analyzed. Under the condition of high ground stress of extrusion, soft rock should be allowed to deform moderately. The stress redistribution of surrounding rock under different supporting strength is studied by avoiding the loading effect of arch surrounding rock and making the supporting structure work in coordination with surrounding rock better. The results show that if the support strength is too large, the stress concentration will be greater in the surrounding rock of the arch roof of the extruded high in-situ stress tunnel. The numerical calculation software of FLAC3D is used to simulate the step excavation construction process of the tunnel by step method. The deformation and stress change of surrounding rock in the course of model test excavation are verified and expanded, and the deformation and stress change of surrounding rock at any position in the middle monitoring section are obtained. Further research suggestions on similar materials, supporting methods and excavation methods are also given.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U456

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