浅埋大断面软岩隧道预留变形量研究

发布时间：2018-08-22 13:13

【摘要】：随着经济建设的发展,国家基础建设的持续投入,高速公路建设已进入新的发展时期,并结合国家一带一路战略,以西南地区为枢纽的交通网将逐步构成,西南山区高等级公路修建过程中,隧道以其能保证运营安全、避免破坏生态环境和关键位置缩短行车里程等优点得到广泛应用。软弱围岩隧道大变形问题是威胁隧道安全的重要问题之一,而解决围岩大变形问题,除了做好支护措施外,确定合理的预留变形量,让围岩释放适当的变形和应力,以保证二次衬砌的安全储备,也是一种方法。相对于复杂的处治围岩大变形的方式,让围岩产生合理的变形量,且在隧道开挖过程中做好预留变形显得更为经济合理。本文以大理海东某隧道为工程研究对象,研究了不同埋置深度和不同围岩级别条件下隧道围岩变形的时空规律及其预留变形量范围,在以后规划实施的施工条件相差不多的工程当中希望可以起到一定的帮助和参考作用。(1)通过对软弱围岩的定义、分类、地质力学特征进行查阅,结合鲁宾涅特公式和本构关系对软岩隧道开挖围岩变形的机理进行了解析,得到隧道开挖围岩变形的一般规律。结合软岩隧道变形规律对软弱围岩隧道开挖预留变形量的确定方法和影响因素进行探究。结合已修建完成的隧道工程分析发现,现有方法针对软岩大变形隧道进行预留变形量确定时都存在一定的问题和不足,在此条件下提出本文的方法和思路。(2)通过对该隧道工程基本状况的了解,在对其围岩地质条件和隧道支护方式详细掌握的前提下,采用MIDAS/GTS构建隧道模型,考虑到围岩变形存在的特点,对V类围岩进行模拟研究时采用蠕变模型。Ⅳ类围岩进行模拟研究时采用弹塑模性型,在不同埋深工况条件下,通过模拟研究分析隧道围岩开挖造成岩体变形移动的时空规律,得到隧道围岩变形模拟数据,在此基础上确定隧道预留变形量的范围值。(3)根据现场监测数据,通过对V级围岩段大量数据统计分析,采用数理统计学知识确定隧道预留变形量取值,结合数值模拟结果综合确定V级围岩段隧道预留变形量为30～35cm, Ⅳ级围岩段预留变形量为15～20cm,并在V级和Ⅳ级围岩段隧道开挖过程中进行验证性应用,通过现场监测分析发现预留量留设效果较好,隧道围岩发生侵限现象大大减少。通过验证表明数值模拟结果具有一定的参考价值。
[Abstract]:With the development of economic construction and the continuous investment of national infrastructure construction, highway construction has entered a new development period, and combined with the national Belt and Road strategy, the traffic network with southwest region as the hub will be gradually constituted. In the process of highway construction in southwest mountainous area, the tunnel has been widely used for its advantages of ensuring the safety of operation, avoiding the destruction of ecological environment and shortening the driving mileage at key locations. The problem of large deformation of soft surrounding rock tunnel is one of the important problems that threaten the safety of tunnel. In order to solve the problem of large deformation of surrounding rock, in addition to supporting measures, the reasonable reserved deformation amount is determined, and the appropriate deformation and stress can be released by surrounding rock. To ensure the safety of secondary lining reserve, is also a method. Compared with the complex treatment of large deformation of surrounding rock, it is more economical and reasonable to make the surrounding rock produce reasonable deformation and make a good reservation of deformation in the course of tunnel excavation. Taking a tunnel in Dali Haidong as an engineering research object, this paper studies the space-time law of surrounding rock deformation and the range of its reserved deformation under different buried depth and different surrounding rock grade. In the future projects with similar construction conditions planned and implemented, we hope to play a certain role in helping and referencing. (1) by referring to the definition, classification, and geomechanical characteristics of weak surrounding rocks, Based on the Rubenet formula and constitutive relation, the deformation mechanism of surrounding rock in soft rock tunnel excavation is analyzed, and the general law of surrounding rock deformation in soft rock tunnel excavation is obtained. Combined with the deformation law of soft rock tunnel, this paper probes into the method of determining the reserved deformation of soft surrounding rock tunnel excavation and the influencing factors. Based on the analysis of the tunnel project that has been built, it is found that the existing methods have some problems and shortcomings in determining the reserved deformation amount of the large deformation tunnel in soft rock. Under this condition, the method and thought of this paper are put forward. (2) based on the understanding of the basic condition of the tunnel project and the detailed understanding of the surrounding rock geological condition and the tunnel supporting mode, the tunnel model is constructed by MIDAS/GTS. Considering the characteristics of surrounding rock deformation, creep model is used in the simulation of V type surrounding rock, and in 鈪，

本文编号：2197198