超小净距隧道原位扩建围岩变形与地表沉降预测方法研究

发布时间：2018-06-12 02:29

本文选题：隧道原位扩建 + 预测　；参考：《华侨大学》2014年硕士论文

【摘要】：近年来，国内外隧道原位扩建工程日益增多。隧道原位扩建工程大多呈现出断面特大、净距超小、扁平率极低等特点，且往往须先拆除既有衬砌，再进行围岩开挖、衬砌施作等工序，易导致结构承载力降低，围岩变形过大，诱发塌方事故。较之于新建隧道，，隧道原位扩建开挖导致的围岩变形及地表沉降更为复杂，如何对其进行合理预测仍是一个十分突出且尚未解决的问题。本文以国内外罕见的大帽山隧道原位2扩4工程为研究背景，通过解析求解、数值模拟、经验公式等3种方法提出隧道原位扩建围岩变形与地表沉降预测方法，对隧道原位扩建工程围岩变形及地表沉降变形规律、卸荷效应下围岩变形及力学特性、围岩力学参数对地表沉降的敏感性进行了系统的研究，对保证类似工程围岩稳定性具有重要的参考价值。主要工作及成果如下： 1、采用等代圆、复变函数理论及Schwarz交替法获得非圆隧道单侧扩建形式下的围岩应力及位移的理论解。据此以大帽山隧道原位2扩4工程为例探讨隧道最优扩挖宽度。 2、基于卸荷理论提出并建立隧道围岩扰动分区（强卸荷扰动区、弱卸荷扰动区及未扰动区）开挖卸荷的计算方法。 3、采用APDL语言编程，将卸荷计算各步骤嵌入ANSYS通用有限元软件，实现卸荷效应下的隧道原位扩建三维数值模拟。 4、以实测数据为据，分析卸荷效应下大帽山隧道原位2扩4工程CD工法下围岩力学及变形特性，围岩强卸荷扰动区、弱卸荷扰动区的分布规律。 5、2扩4隧道对已建4车道隧道结构变形影响为：4车道隧道左侧围岩处于卸荷扰动区范围内，左侧变形较右侧大，隧道断面呈现明显的偏压。 6、围岩力学参数对隧道原位扩建地表沉降的敏感程度为： E c。 7、采用Peck公式、叠加原理提出扩建隧道地表沉降的简便预测公式，并验证函数关系式的适用性。
[Abstract]:In recent years, the domestic and foreign tunnel in situ expansion project is increasing day by day. Most of the in-situ expansion projects of tunnel show the characteristics of super large section, super-small net distance and extremely low flat rate, and it is often necessary to remove the existing lining first, then excavate the surrounding rock and construct the lining, which will easily lead to the reduction of the bearing capacity of the structure. The deformation of surrounding rock is too large, which induces collapse accident. Compared with the new tunnel, the surrounding rock deformation and surface settlement caused by in-situ tunnel expansion and excavation are more complex. How to predict it reasonably is still a very outstanding and unsolved problem. In this paper, based on the domestic and foreign rare in situ 2 expansion 4 project of Tai Mo Shan Tunnel as the research background, through analytical solution, numerical simulation, Three methods, such as empirical formula, are put forward to predict the deformation of surrounding rock and surface settlement of tunnel in situ expansion. The deformation and mechanical properties of surrounding rock under unloading effect are studied. The sensitivity of mechanical parameters of surrounding rock to surface subsidence is studied systematically, which is of great reference value to guarantee the stability of surrounding rock of similar engineering. The main work and results are as follows: 1. The theoretical solution of surrounding rock stress and displacement in the form of unilateral expansion of non-circular tunnel is obtained by using the theory of equivalent circle, complex variable function and Schwarz alternating method. Based on this, the optimal width of tunnel expansion and excavation is discussed by taking the in-situ 2 extension 4 project of Tai Mo Shan Tunnel as an example. 2. Based on the unloading theory, the disturbance zone of surrounding rock of the tunnel (strong unloading disturbance zone) is proposed and established. The calculation method of excavating unloading in weak unloading disturbed zone and undisturbed zone). 3. Using APDL programming language, the unloading calculation steps are embedded in ANSYS universal finite element software. Three-dimensional numerical simulation of in-situ tunnel expansion under unloading effect is realized. 4. Based on the measured data, the mechanical and deformation characteristics of surrounding rock and the disturbed zone of strong unloading of surrounding rock are analyzed under the CD method of in-situ extension 4 project of Damaoshan Tunnel under unloading effect. The distribution of the weak unloading disturbance zone. The influence of the structure deformation on the existing 4-lane tunnel is that the surrounding rock on the left side of the four-lane tunnel is in the range of unload disturbance, and the deformation on the left side is larger than that on the right side. The tunnel section shows obvious bias voltage. 6. The sensitivity of surrounding rock mechanics parameters to the ground settlement of in-situ expansion of tunnel is: E.7. by using Peck formula and superposition principle, a simple prediction formula for ground subsidence of extended tunnel is put forward. The applicability of the function relation is verified.
【学位授予单位】：华侨大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U452.1;TU43

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