大断面隧道超前预加固及开挖支护过程数值模拟研究

发布时间：2018-11-08 19:25

【摘要】：摘要：在我国,许多隧道是软弱围岩地段的大断面浅埋隧道,这类隧道在施工过程中经常发生隧道塌方、冒顶等事故,给隧道建设带来很大困扰。预加固大断面隧道施工工法能较好的解决隧道围岩软弱、掌子面容易失稳等问题。随着断面的增大,掌子面的稳定成为了开挖稳定的控制性因素之一。论文以FLAC3D为数值模拟手段,主要进行了以下几个方面的工作： 1.总结国外大跨隧道超前预加固的研究经验,简要阐述了岩土控制变形分析(ADECO-RS)方法(新意法)的基本理念。 2.通过数值模拟计算了II-VI级围岩条件下大断面隧道的开挖情况,研究了相应各种情况下掌子面的变形、塑性区分布、破坏特征以及拱顶位移及地层变形情况。并模拟了隧道断面尺寸、隧道埋深对掌子面稳定性的影响。采用棚式支护、玻璃纤维锚杆的方法和劈裂注浆对掌子面进行加固。 3.在软岩大断面隧道开挖过程中,如果没有初期支护以及对超前核心围岩进行加固,只采用大管棚预加固时,其梁拱效应不明显,超前核心围岩的变形仍然较大,掌子面不能保持稳定。超前玻璃锚杆及注浆均能显著提高核心土自身的强度和刚度,大大减小塑性区的深度。 4.提出适合的超前预加固方式。运用FLAC3D有限差分软件,模拟经超前预加固后对掌子面变形、隧道收敛、塑性区分布、地表沉降的影响。在软弱围岩等不良地质条件下,通过对掌子面前方核心土进行预加固以及掌子面外的预注浆支护,可以明显的提高核心土的强度并改善其受力情况,显著的减少掌子面的变形和缩小塑性区范围,减小了隧道的预收敛,提高了施工过程中工作面的稳定性。
[Abstract]:Absrtact: in our country, many tunnels are large section shallow buried tunnels in weak surrounding rock area, such as tunnel collapse and roof fall often occur in the construction process of this kind of tunnel, which brings great trouble to tunnel construction. Pre-reinforcement of large section tunnel construction method can better solve the tunnel surrounding rock weakness, face instability and other problems. With the increase of the section, the stability of the face becomes one of the controlling factors of the stability of excavation. In this paper, FLAC3D is used as a numerical simulation method, the main work is as follows: 1. This paper summarizes the research experience of advanced pre-reinforcement of long-span tunnels abroad, and briefly expounds the basic idea of geotechnical deformation control analysis (ADECO-RS) method (Xinyi method). 2. The excavation of large-section tunnel under the condition of II-VI grade surrounding rock is numerically simulated, and the deformation, plastic zone distribution, failure characteristics, arch displacement and formation deformation of the face are studied. The influence of tunnel section size and tunnel depth on the stability of the face is simulated. The face of the face is strengthened by the method of sheathing support, glass fiber bolt and split grouting. 3. In the excavation process of large section tunnel in soft rock, if there is no initial support and reinforcement of the leading core rock, the beam and arch effect is not obvious and the deformation of the leading core rock is still large when only the large pipe shed is used to pre-reinforce the tunnel. The face of the palm is not stable. The strength and stiffness of the core soil can be significantly improved by advanced glass bolt and grouting, and the depth of plastic zone can be greatly reduced. 4. A suitable way of pre-reinforcement is put forward. In this paper, FLAC3D finite difference software is used to simulate the influence of the pre-reinforcement on the surface deformation, tunnel convergence, plastic zone distribution and surface settlement. Under the bad geological conditions such as soft surrounding rock, by pre-strengthening the core soil in front of the face and pre-grouting support outside the face of the face, the strength of the core soil can be obviously improved and the stress situation of the core soil can be improved. The deformation of the face is reduced and the range of the plastic zone is reduced, the pre-convergence of the tunnel is reduced, and the stability of the working face in the construction process is improved.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U455.49

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