摩围山隧道围岩稳定性分析

发布时间：2018-04-03 01:25

本文选题：小净距隧道　切入点：V级围岩　出处：《西南交通大学》2015年硕士论文

【摘要】：伴随社会经济水平的不断提升,交通等基础设施领域的建设也必将蓬勃开展。交通领域的建设,特别是在山区丘陵地带,必然会修建大量的隧道工程。在当下隧道工程建设中主要的建造形式有分离式隧道、连拱隧道和小净距隧道。在地形地貌、地质条件复杂地区修建隧道工程,由于各方面条件的限制,大都不得以压缩两洞间距离,选择连拱或小净距形式修建隧道。小净距施工安全性较高,造价相对低廉,长期可靠性有保障并且其施工技术要求不高,这些优点使得小净距隧道受到越来越多的重视,也成为了山区特殊地质及地形条件下隧道工程的主要形式之一,这也促使工程界对小净距隧道施工特点方面开展了众多的研究。本文以摩围山隧道为依托工程,具体针对该隧道Ⅴ级围岩段地质条件较复杂、浅埋和小净距的特点,从研究隧道开挖后围岩的应力分布特点、变形特征和隧道掌子面施工间距等出发,研究在V级围岩条件下小净距隧道的施工过程中的监控重点及围岩稳定性。通过模拟分析发现：采用CRD法开挖小净距隧道,在开挖完成上半部分后围岩在拱腰和拱脚处形成应力集中区,在下半部分的开挖过程中应力集中区向拱脚移动且最大值进一步增加。小净距隧道两洞在开挖过程中相互影响,尤其是两洞之间夹岩处受影响最为强烈形成相连的应力集中区域,而对于应变而言由于后行洞的施工使得隧道围岩竖向位移也进一步增加,由于隧道浅埋施工时应密切注意避免冒顶。对不同的隧道开挖间距,通过对比分析发现小净距隧道的施工间距不能过小,因为过小围岩的位移和应力值都会受到影响,每个施工步的应力及位移变化都大幅增加,这对围岩的稳定性非常不利,如果开挖造成的扰动超过围岩的最大承受能力时,隧道围岩破坏甚至失稳就非常可能发生；而随着隧道施工间距的增大,又不能很好的把握施工工期。所以选取合理的小净距隧道两洞间的施工间距是极其有必要的,应当综合考虑不同掌子面施工间距下的分析成果和项目工期来确定工程的合理施工间距。本文的研究成果,对今后类似的工程实践具有一定的参考意义。
[Abstract]:With the continuous improvement of social and economic level, the construction of infrastructure such as transportation is bound to flourish.Traffic construction, especially in hilly areas, is bound to build a large number of tunnel projects.In the current tunnel construction, the main construction forms are split tunnel, multi-arch tunnel and small clearance tunnel.Because of the limitation of various conditions, it is not possible to construct the tunnel in the form of double arch or small net distance by reducing the distance between the two holes in the construction of tunnel engineering in the area of topography and geomorphology and complex geological conditions.The small net distance tunnel is paid more and more attention because of its high safety, low cost, long term reliability and low technical requirement.It has also become one of the main forms of tunnel engineering under special geological and topographic conditions in mountainous areas, which has prompted the engineering community to carry out numerous studies on the construction characteristics of small spacing tunnels.In this paper, based on the project of Mowei Mountain Tunnel, aiming at the complex geological conditions, shallow burying and small distance of surrounding rock, the stress distribution of surrounding rock after excavation of the tunnel is studied.Based on the deformation characteristics and construction spacing of tunnel face, this paper studies the monitoring emphasis and the stability of surrounding rock in the construction process of small clear distance tunnel under the condition of V class surrounding rock.Through simulation analysis, it is found that CRD method is used to excavate the small net distance tunnel, and the surrounding rock forms a stress concentration zone at the arched waist and arch foot after the excavation of the upper half of the tunnel.During the excavation of the lower part, the stress concentration area moves to the arch foot and the maximum value increases further.The interaction between the two holes in the small spacing tunnel during the excavation process, especially the stress concentration area where the rock intercalation between the two holes is most strongly affected, is formed.For strain, the vertical displacement of surrounding rock is further increased due to the construction of the rear tunnel, and the roof fall should be avoided when the tunnel is shallowly buried.For the different tunnel excavation spacing, it is found that the construction spacing of the tunnel should not be too small, because the displacement and stress value of the small surrounding rock will be affected, and the stress and displacement changes of each construction step will increase greatly.This is very unfavorable to the stability of surrounding rock. If the disturbance caused by excavation exceeds the maximum bearing capacity of surrounding rock, the failure and even instability of tunnel surrounding rock are likely to occur, and with the increase of tunnel construction spacing,Also can not very good grasp the construction period.Therefore, it is extremely necessary to select reasonable construction spacing between two holes in a small net distance tunnel. The reasonable construction spacing should be determined by considering the analysis results under different face construction spacing and the project duration.The research results of this paper have certain reference significance to similar engineering practice in the future.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U451.2

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