兰州地铁浅埋砂卵石地层盾构掘进稳定性分析

发布时间：2018-03-25 05:00

本文选题：盾构法　切入点：砂卵石地层　出处：《兰州交通大学》2015年硕士论文

【摘要】：盾构法在隧道施工中的应用越来越普遍,其施工过程不可避免地会引起地层的移动和变形。目前,对砂卵石地层中盾构施工地层变形规律和控制方法研究较少,缺乏可供参考的研究成果。卵石地层是一种典型的力学不稳定层,表现出颗粒间点点接触传力,易受扰动,灵敏度高,结构松散且无粘聚力。因此对卵石地层中盾构开挖稳定性的研究十分必要。本文以兰州地铁隧道的盾构施工为研究背景,紧密结合兰州城区试验段盾构隧道所在位置特有的工程地质及水文地质条件,对卵石地层中盾构开挖过程中开挖面的稳定性进行了深入研究,主要研究内容如下:1、以工程地质与经典土力学理论为基础,分析了盾构施工引起隧道上方地层变形与失稳的规律,提出采用地表竖向设置锚杆预加固的技术手段进行超前地层加固。目前,这种加固理念较少用于盾构式隧道开挖施工中,其应用成果将为兰州地铁后续隧道施工及其他类似工程施工提供重要参考,具有创新性和较高的工程应用价值。2、根据砂卵石地层太沙基有效松动土压力计算理论,结合兰州地铁隧道试验段的地层条件,计算了隧道上覆土压力。采用极限分析理论,结合楔型土体压力计算模型,提出保证盾构施工中开挖面土体稳定性的支护力计算公式,确定了盾构施工中推进力和隧道开挖面支护力的安全范围,为有效降低隧道施工引起的地表下沉或隆起提供了可靠的理论依据。3、以兰州地铁为背景,对锚杆预加固的加固机理及效果进行理论分析和计算,得出设置竖向锚杆可在不同程度提高地层土体的粘聚力和内摩擦角,减小开挖面的支护压力,从而有效提高砂卵石地层的强度及开挖面的稳定性。4、借助有限分差计算软件FLAC 3D,模拟分析锚杆竖向加固作用效果,并通过调整锚杆入土深度和布设间距,进行锚杆加固效果对比。
[Abstract]:The application of shield method in tunnel construction is becoming more and more common, and the construction process will inevitably lead to the movement and deformation of stratum. At present, there are few researches on deformation law and control method of shield construction stratum in sand pebble stratum. The pebble stratum is a kind of typical mechanical instability layer, which shows contact force between particles, is easily disturbed, and has high sensitivity. The structure is loose and there is no cohesion. So it is necessary to study the stability of shield tunneling in pebbles. This paper takes the shield construction of Lanzhou subway tunnel as the research background. Based on the engineering geological and hydrogeological conditions of the location of shield tunnel in Lanzhou urban test section, the stability of excavating surface during the excavation of shield in pebble strata is studied in depth. The main research contents are as follows: 1. Based on engineering geology and classical soil mechanics theory, the law of ground deformation and instability caused by shield tunneling is analyzed. This paper puts forward the technical means of pre-reinforcement of ground surface vertical bolting. At present, this kind of reinforcement concept is seldom used in the excavation of shield tunnel. The application results will provide an important reference for the construction of Lanzhou Metro follow-up tunnel and other similar projects, and have innovative and high engineering application value .2.According to the calculation theory of effective loose soil pressure of Taishaji in sand pebble formation, Combined with the formation conditions of the experimental section of Lanzhou Metro Tunnel, the overlying earth pressure of the tunnel is calculated. By using the limit analysis theory and the calculation model of the wedge soil pressure, the formula for calculating the supporting force to ensure the stability of the excavated surface in shield tunneling is put forward. The safe range of propelling force and tunnel excavation support force in shield construction is determined, which provides a reliable theoretical basis for effectively reducing the surface subsidence or uplift caused by tunnel construction, taking Lanzhou Metro as the background. Through theoretical analysis and calculation of reinforcement mechanism and effect of pre-reinforcement of anchor rod, it is concluded that setting vertical anchor rod can increase cohesion and internal friction angle of soil in different degree, and reduce the support pressure of excavated surface. In order to effectively improve the strength of sand pebble formation and the stability of excavated surface. With the help of finite difference calculation software FLAC 3D, the effect of vertical reinforcement of anchor rod is simulated and analyzed, and the depth and spacing of anchor rod are adjusted. The effect of anchor reinforcement is compared.
【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】：U231.3;U455.43

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