大断面连拱隧道中隔墙力学行为及稳定性研究

发布时间：2018-06-13 15:02

本文选题：大断面 + 连拱隧道　；参考：《重庆交通大学》2015年硕士论文

【摘要】：随着我国国民经济的快速发展,大断面连拱隧道作为一种新型的结构形式已被广泛采用。但由于其结构失跨比小,跨度大,隧道结构施工过程受力状态远比一般连拱隧道复杂。中隔墙是连拱隧道结构受力的核心构件,拉、压、弯、剪、扭均有,同时左右洞施工对中隔墙影响,增加了施工变形和稳定的控制,中隔墙的力学行为直接关系到隧道整体结构的稳定性。因此,深入分析研究中隔墙力学行为及变形特征和稳定性影响因素,对大断面连拱隧道的设计和施工具有指导意义。本文依托贵阳遵义中路隧道工程为背景,对目前国内外普遍采用的六种中隔墙形式,在支护参数、中墙宽度、高度、围岩类别均相同的情况下,运用ANSYS12.0建立四个二维平面有限元模型,分析他们各自受力变形规律和结构安全系数。接着对连拱隧道中隔墙的施工过程建立三维空间有限元模型,对连拱隧道开挖时中隔墙的力学行为及变形特性、左右洞的相互影响进行了分析,同时在原有施工步骤上,中墙一侧、顶部是否回填对中隔墙稳定性进行分析。主要研究成果包括:1收集连拱隧道中隔墙断面形式,分析各个断面形式的优缺点和适用条件,为连拱隧道中隔墙断面选择提供参考。2通过对六种中隔墙形式二维模拟,得出各中隔墙施工结束都处于偏压状态,分层直中墙偏压受力最大,且各中隔墙结构都是安全的,整体曲中墙安全系数最大,中空直中墙安全系数最小。3中隔墙在施工过程中一直处于偏压状态,其竖向应力呈台阶式收敛,各施工工序对中墙凹处的竖向应力影响变化幅度最大,底部竖向应力影响变化幅度最小,各截面中墙中心测点变化平缓。4采用中导洞—台阶法开挖时,左洞开挖掌子面影响范围18m,右洞开挖掌子影响范围24m,提出了软弱围岩大断面连拱隧道中两洞开挖掌子面合理间距为2B(单洞开挖跨度为15m)。5采用中导洞—台阶法开挖时,左洞施工对中隔墙应力的影响范围为18m,右洞施工对中隔墙的应力影响范围为27m。6在原有施工步骤下,采取在中隔墙顶部回填右侧回填、中隔墙顶部回填右侧不回填和中隔墙顶部不回填右侧不回填3种情况模拟分析中隔墙稳定性影响因素,得出中隔墙顶部右侧均回填有利于中墙稳定。
[Abstract]:With the rapid development of China's national economy, large section multi-arch tunnel has been widely used as a new type of structure. However, due to its small span loss ratio and large span, the stress state of tunnel structure is much more complicated than that of common multi-arch tunnel. The middle partition wall is the core component of the structure of the multi-arch tunnel. There are tension, compression, bending, shear and torsion. At the same time, the construction of the left and right tunnels has an effect on the middle partition wall, which increases the construction deformation and stability control. The mechanical behavior of the middle partition wall is directly related to the stability of the whole tunnel structure. Therefore, it is of guiding significance for the design and construction of large-section multi-arch tunnel to deeply analyze the mechanical behavior, deformation characteristics and influence factors of stability of the partition wall. Based on the background of Guiyang Zunyi Middle Road Tunnel Project, this paper introduces six types of middle partition wall which are widely used at home and abroad, under the condition of the same supporting parameters, middle wall width, height and surrounding rock type. Four two-dimensional finite element models are established by using ANSYS12.0, and their stress and deformation laws and structural safety factors are analyzed. Then the three-dimensional finite element model is established for the construction process of the partition wall in the multi-arch tunnel. The mechanical behavior and deformation characteristics of the partition wall during the excavation of the multi-arch tunnel and the interaction between the left and right tunnels are analyzed. At the same time, the original construction steps are also discussed. The stability of the middle wall is analyzed by backfilling on the side of the middle wall and the top of the wall. The main research results include: 1 collect the cross-section form of partition wall in multi-arch tunnel, analyze the advantages and disadvantages and applicable conditions of each section form, and provide reference for the selection of partition wall section in multi-arch tunnel through the two-dimensional simulation of six kinds of middle partition wall form. It is concluded that the construction of each middle partition wall is in a state of bias, and the eccentric force of the layered straight middle wall is the largest, and the structure of each middle partition wall is safe, and the safety factor of the integral curved middle wall is the largest. The minimum safety factor of hollow straight middle wall is 3. 3. The middle partition wall has been in the state of bias during the construction process, and its vertical stress converges step by step, and the influence of each construction procedure on the vertical stress in the middle wall concave is the greatest. The effect of vertical stress on the bottom is the smallest, and the change of measuring point in the center of each section of the wall is gentle. 4. When excavating with the method of mid-guide cavern and step method, The influence range of left hole excavation face and right hole excavation palm face is 18m and 24m respectively. The reasonable distance between the excavation face of the two holes in the large-section multi-arch tunnel with weak surrounding rock is 2B (the single hole excavation span is 15m).5) when the mid-guide cave-step method is used to excavate the tunnel. The influence range of the left hole construction on the stress of the middle partition wall is 18 m, and the influence range of the right hole construction on the middle partition wall stress is 27m.6. Under the original construction steps, the right side backfill is adopted at the top of the middle partition wall. In the simulation analysis of the factors affecting the stability of the partition wall, it is concluded that the backfilling on the top side of the middle partition wall is beneficial to the stability of the middle wall in the simulation analysis of the three situations of no backfilling on the top of the middle partition wall and no backfilling on the right side of the top of the middle partition wall.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U451;U455

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