铁路隧道底部结构隆起变形及其工程对策研究

发布时间：2018-01-07 02:33

本文关键词：铁路隧道底部结构隆起变形及其工程对策研究　出处：《北京交通大学》2016年硕士论文　论文类型：学位论文

【摘要】：我国新建铁路隧道大部分采用无砟轨道,对隧道底部变形的要求非常严格。运营和在建的铁路隧道常有底部隆起变形发生,给行车安全和工程建设带来很大困难,急需深入研究并加以解决。但是,由于隧道底部结构隆起变形的机理非常复杂,目前尚缺乏合理的力学分析基础,以及相应的工程对策。所以,研究铁路隧道底部结构隆起变形机理以及工程对策具有重要意义。本文首先通过调查国内外的铁路隧道底部隆起变形事例以及相关的岩石强度试验结果,分析铁路隧道底部结构隆起的影响因素和变形机理：然后,以兰新铁路福川隧道为背景,采用数值模拟的手段,研究含有少量膨胀性黏土矿物的沉积岩地质条件下铁路隧道底部隆起现象：最后,分析抑制铁路隧道底部结构隆起变形的工程对策。主要研究成果如下：(1)通过文献调查和资料收集,对铁路隧道底部结构隆起变形的发生条件进行梳理,从地质岩性、围岩受力以及地下水等方面进行分析,明确了隧道底部隆起变形的机理主要有两大类,即隧道底部围岩的塑性变形(squeezing)和吸水膨胀(swelling)。(2)根据既往的有关沉积岩强度的试验结果,发现含水率对岩体强度,特别是泥岩、泥质砂岩以及凝灰岩等沉积岩的强度有较大的影响,含水率增大会显著降低岩体的强度。(3)在弹粘塑性理论的基础上,采用强度劣化有限元模型分析了铁路隧道底部结构隆起变形的力学机理。隧道底部围岩,由于含水率的增加,可能导致围岩强度的降低,使得底部围岩的塑性变形增大,引起底部结构隆起变形。(4)依据强度劣化理论模型,采用数值模拟的手段,模拟兰新铁路福川隧道底部隆起现象。根据仰拱厚度不同分两种工况,得出随着围岩粘聚力的降低,底部结构隆起变形逐渐增大,底部拉应力数值和范围逐渐增大,底部结构和围岩塑性区也逐渐增大；仰拱厚度的不足使得围岩强度劣化引起的底部结构隆起变形更加显著。得到的隆起变形量以及仰拱填充层开裂的结果大致与现场监测结果相符。(5)以兰新铁路福川隧道为模型,通过数值模拟研究铁路隧道底部结构隆起的工程对策,得出仰拱曲率的增大可以有效抑制围岩强度劣化引起的底部结构隆起变形。
[Abstract]:Most of the new railway tunnels in our country use ballastless track, which is very strict to the deformation of the bottom of the tunnel. The railway tunnel in operation and under construction often has the bottom uplift deformation. It brings great difficulties to traffic safety and engineering construction, and needs to be studied and solved. However, due to the complex mechanism of the uplift and deformation of the bottom structure of the tunnel, there is still a lack of a reasonable basis for mechanical analysis. And the corresponding engineering countermeasures. So... It is of great significance to study the deformation mechanism and engineering countermeasures of railway tunnel bottom structure uplift. Firstly, through investigation of domestic and foreign railway tunnel bottom uplift deformation cases and related rock strength test results. The influence factors and deformation mechanism of the railway tunnel bottom structure uplift are analyzed. Then, taking the Lanxin Railway Fuchuan Tunnel as the background, the method of numerical simulation is adopted. This paper studies the uplift of the bottom of railway tunnel under the geological conditions of sedimentary rocks containing a small amount of expansive clay minerals: finally. The main research results are as follows: 1) through literature investigation and data collection, the paper combs the occurrence conditions of railway tunnel bottom structure uplift deformation. Based on the analysis of geological lithology, stress of surrounding rock and groundwater, it is clear that there are two main types of deformation mechanism of tunnel bottom uplift. That is, plastic deformation of the surrounding rock at the bottom of the tunnel) and water absorption and expansion are based on the results of previous tests on the strength of sedimentary rocks. It is found that water content has great influence on the strength of rock mass, especially mudstone, argillaceous sandstone and tuff. On the basis of elastic-viscoplastic theory, the strength degradation finite element model is used to analyze the mechanical mechanism of the uplift and deformation of the railway tunnel bottom structure, and the surrounding rock at the bottom of the tunnel. Due to the increase of water content, the strength of surrounding rock may be reduced, and the plastic deformation of the bottom rock will increase, which will cause the uplift deformation of the bottom structure. (4) according to the theoretical model of strength degradation, the method of numerical simulation is adopted. Simulation of Lanxin Railway Fuchuan Tunnel bottom uplift phenomenon. According to the thickness of inverted arch is divided into two working conditions, it is concluded that with the decrease of surrounding rock cohesion, the bottom structure uplift deformation increases gradually. The value and range of the bottom tensile stress increase gradually, and the plastic zone of the bottom structure and surrounding rock increases gradually. The deformation of the bottom structure caused by the deterioration of the surrounding rock strength is more significant due to the insufficient thickness of the inverted arch, and the result of the uplift deformation and the crack of the infill layer of the inverted arch are roughly consistent with the field monitoring results. Take Fuchuan Tunnel of Lanxin Railway as the model. Through numerical simulation the engineering countermeasures of the uplift of the bottom structure of the railway tunnel are studied. It is concluded that the increase of the curvature of the inverted arch can effectively restrain the uplift deformation of the bottom structure caused by the deterioration of the surrounding rock strength.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U457.2

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