大华山隧道围岩稳定性及结构可靠度研究

发布时间：2018-11-09 12:33

【摘要】：随着西部大开发战略稳步实施，我国交通基础设施建设得到了高速发展，给公路建设带来了前所未有的机遇和挑战。由于隧道工程具有独特的优势，因而在公路工程中被广泛的应用，并且取得了良好的社会经济效益。但是由于隧道支护结构通常所处的地质环境条件一般都比较复杂，，围岩力学参数指标、计算模式、荷载和结构抵抗能力等比较难确定，使得目前采用传统的隧道支护结构的设计方法难以同时兼顾断面形式的经济合理性和支护结构的稳定性，具有一定的盲目性。因此，用结构可靠度理论来研究分析隧道支护结构的稳定可靠性，使隧道设计更加合理、科学，减少运营期间隧道的安全隐患，具有十分重要的实践和理论意义。 本文在大量阅读和参考国内外相关文献的基础上，依托国家高速公路网郧县至十堰高速公路大华山隧道，通过对隧道区工程地质条件的研究，结合现场对围岩拱顶下沉和洞周收敛变形的监测，并对监测数据进行处理分析，利用FLAC3D建立隧道模型，对大华山隧道施工开挖过程中围岩应力应变特征进行分析，为施工中采用合理的支护提供依据。同时，建立功能函数及各参变量分布形态，采用蒙特卡罗法对大华山隧道支护结构进行可靠度研究。本文的主要内容和取得成果如下： （1）深入研究了隧道开挖过程中力学特性，分析了围岩应力、应变的变化过程，从地质因素、工程因素两大方面分析了影响大华山隧道围岩稳定性的不利因素，得出地下水、时间因素对大华山围岩稳定性影响比较大。 （2）分析了隧道支护结构失稳破坏的原因和收敛比、变形速率比值、容许极限位移和变形速率与加速度等四种常用失稳判据，在此基础上通过对大华山隧道Ⅳ级与Ⅲ级围岩的相交围岩段的围岩变形监测数据进行回归分析，得出此段围岩变形趋于稳定的时间节点为27天左右，为隧道二衬施作时间提供参考依据。 （3）采用FLAC3D软件对大华山隧道施工过程进行了数值模拟，对开挖过程中隧道的应力、应变进行了分析，得出隧道位移变形量与现场监测数据基本一致。并找出隧道拱腰（上下台阶开挖分界处）、拱顶和拱脚部位是围岩稳定性的薄弱部位，为隧道后续施工和监测提供指导。 （4）基于MATLAB软件采用蒙特卡洛算法和设计验算点法计算比较各种工况下的可靠指标并对其分析，得出隧道支护结构是稳定的，采用的支护结构是合理的，为大华山特长隧道围岩稳定性评价及其支护技术提供理论依据和科学指导，也对其他类似工程施工有一定的借鉴和指导意义。
[Abstract]:With the steady implementation of the strategy of western development, the construction of transportation infrastructure in China has been developing at a high speed, which has brought unprecedented opportunities and challenges to highway construction. Because of its unique advantages, tunnel engineering has been widely used in highway engineering, and has achieved good social and economic benefits. However, because the geological environment of tunnel support structure is usually complicated, it is difficult to determine the mechanical parameters of surrounding rock, the calculation model, the load and the resistance of the structure, etc. It is difficult to take account of the economic rationality of section form and the stability of supporting structure at the same time because of the traditional design method of tunnel support structure, which is blind to a certain extent. Therefore, it is of great practical and theoretical significance to use the theory of structural reliability to study and analyze the stability and reliability of tunnel support structure, to make the tunnel design more reasonable and scientific, and to reduce the hidden danger of tunnel safety during operation. On the basis of reading and referring to domestic and foreign related documents, this paper, relying on the national highway network Yun county to Shiyan highway Dahuashan tunnel, through the study of the tunnel area engineering geological conditions, Combined with the site monitoring of surrounding rock arch roof subsidence and convergence deformation around the tunnel, the monitoring data are processed and analyzed, and the tunnel model is established by using FLAC3D to analyze the stress and strain characteristics of surrounding rock during the construction and excavation of Dahuashan Tunnel. It provides the basis for reasonable support in construction. At the same time, the function and the distribution form of each parameter are established, and the reliability of the supporting structure of Dahuashan tunnel is studied by Monte Carlo method. The main contents and achievements of this paper are as follows: (1) the mechanical characteristics of tunnel excavation are deeply studied, and the variation process of stress and strain of surrounding rock is analyzed. The unfavorable factors affecting the stability of surrounding rock of Dahuashan Tunnel are analyzed in two aspects of engineering factors. It is concluded that the groundwater and time factors have great influence on the stability of surrounding rock of Dahua Mountain. (2) the causes and convergent ratio, the ratio of deformation rate, the allowable limit displacement and deformation rate and acceleration are analyzed. On this basis, through the regression analysis of the surrounding rock deformation monitoring data of the intersection of grade 鈪

本文编号：2320429