浅埋偏压小净距隧道施工方案优化与稳定性分析

发布时间：2018-02-13 10:09

  本文关键词： 浅埋偏压 小净距隧道 反压护拱 数值模拟 稳定性　出处：《长沙理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：随着我国交通事业的迅猛发展和绿色环保、自然和谐设计理念的广泛普及,小净距隧道以其独特的优势被广泛应用于山区公路隧道的修建中。小净距隧道洞口段地质条件恶劣,受埋深浅和地形偏压的不利因素影响,围岩自稳能力差,开挖后,收敛变形大,成洞困难,容易产生塌方冒顶事故,是隧道施工中的控制性地段。如何采取经济合理的辅助施工措施与开挖方法,在确保施工安全的前提下,减小浅埋和偏压对隧道稳定的不利影响,是浅埋偏压小净距隧道在设计和施工中面临的关键问题。本文以温州市苍南县藻溪隧道为工程背景,在参阅大量相关文献资料的基础上,针对上述问题进行了系统的分析和研究。(1)详细总结了隧道偏压处治技术和浅埋隧道的开挖方法。介绍了弹塑性力学理论和Flac~(3D)软件建模的基础知识。(2)利用数值模拟软件Flac~(3D)研究了反压护拱对浅埋偏压小净距隧道稳定性的影响,通过分析不同厚度反压护拱下隧道围岩的位移、应力集中系数和塑性区的分布情况,得到了Ⅳ级和Ⅴ级围岩反压护拱的最优厚度,为反压护拱施工方案的优化提供了可靠依据。(3)对Ⅳ级和Ⅴ级围岩进行了不同开挖方法的数值模拟,通过对比隧道最终的稳定性,优选出了合理的开挖方案。(4)研究了优选开挖方案的施工过程,通过分析开挖过程中围岩关键点和中夹岩柱位移的变化情况,围岩应力集中区和塑性区的分布情况,了解隧道在施工过程中的薄弱环节,为科学指导施工提供依据。本文立足于学科前沿,采用先进的数值计算方法与分析手段,对反压护拱偏压挡墙的厚度以及隧道开挖方案的优化进行了研究,具有较高的工程应用价值,为系统开展浅埋偏压小净距隧道的稳定性研究提供了一种有效的分析手段。
[Abstract]:With the rapid development of transportation and environmental protection in our country, and the widespread popularization of the concept of natural harmony design, the small clear distance tunnel is widely used in the construction of highway tunnel in mountainous area because of its unique advantages. The geological conditions of the entrance section of the small clear distance tunnel are poor. Affected by the unfavorable factors of buried depth and topographic bias, the self-stability of surrounding rock is poor. After excavation, the convergence deformation is large, the formation of tunnel is difficult, and the caving accident is easy to occur. It is a controlling section in tunnel construction. How to adopt economical and reasonable auxiliary construction measures and excavation methods to reduce the adverse effects of shallow burying and bias pressure on tunnel stability under the premise of ensuring construction safety, This paper takes Chaoxi Tunnel in Cangnan County of Wenzhou City as the engineering background, and on the basis of consulting a large number of related documents, it is the key problem in the design and construction of shallow bias voltage and small clear distance tunnel. This paper makes a systematic analysis and research on the above problems. (1) summarizes in detail the treatment technology of tunnel bias and the excavation method of shallow tunnel, introduces the theory of elastoplastic mechanics and the basic knowledge of software modeling of Flacan 3D), and makes use of numerical simulation. Software Flacan 3D) is used to study the effect of reverse pressure arch on the stability of tunnel with shallow bias voltage and small clear distance. Based on the analysis of the displacement, stress concentration factor and the distribution of plastic zone of the surrounding rock under the tunnel arch with different thickness, the optimum thickness of the 鈪，

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