八字岭分岔隧道稳定性分析及其安全控制

【作者】 王书刚；

【导师】 李术才；

【作者基本信息】 山东大学 ， 岩土工程， 2006， 硕士

【摘要】 分岔隧道是一种较为新颖而结构特殊的隧道形式，即一端洞口为四车道大拱，中间经过连拱段和小间距段，直到另一端洞口为上下行分离隧道。由于分岔隧道具有其适用于崇山峻岭、地形复杂的山区，空间利用率较高以及综合造价低等特点，是目前在特定条件下修建隧道的理想选择之一。但是现在对分岔隧道的研究和应用还处在摸索和初级阶段，缺乏系统和全面的研究，导致其设计理论和施工方法还尚不成熟。 本文以正在建设的沪蓉国道主干线湖北省境内宜昌至恩施段八字岭隧道为工程背景和主要研究对象，应用现场监控量测和数值计算相结合的方法，对国内研究不足的分岔隧道的施工工法、岩柱厚度、爆破震动等方面进行深入细致的研究，提出了切实可行的工程技术措施以保证工程的长期稳定性，研究成果可为分岔式隧道的设计和施工服务。 本文详细的阐述了八字岭隧道施工现场监控量测的方法、内容以及监测项目的布置形式、位置等内容，并通过实测数据和结果的整理分析，对八字岭隧道施工过程中围岩变形（包括围岩位移、周边收敛、拱顶下沉等），以及衬砌、初期支护的受力进行了分析，一方面作为施工监测，保证八字岭隧道的安全顺利施工，对检验设计的合理性提供了有益的参考；另一方面，作为科研监测，得到了分岔隧道施工中围岩和支护系统的受力和变形规律，可为同类工程提供有益的借鉴。 其次，采用FLAC^3D分别对大拱段、连拱段、小间距段进行了爆破震动数值计算。计算了不同药量、不同爆破部位以及临近施工爆破作用下，隧道围岩的应力场、位移场和速度场的分布规律，得出了不同位移类别不同开挖方式下的最大单段装药量，采用质点峰值速度指标给出了最小间距，为今后实际工程提供了借鉴和参考。 最后，从施工过程力学角度，运用FLAC^3D对小间距段进行了三维稳定性分析，通过结果分析，得出了不同围岩类别的开挖方式；给出了Ⅳ类围岩条件下，两隧道开挖的合理步距；通过比较无锚、加锚的计算结果，证明了实际加锚的有效性，得出了一些有益的结论。更多还原

【Abstract】 Branched tunnel is a novel tunnel form with special structure. It is made up of four parts. One end is a big-arch section for four-lane; the other end is two separated tunnels; the middle includes double-arch section and small spacing section. Now branched tunnel is one of the best ways to build tunnels due to its many advantages such as high flexibility to mountain chain of precipitous topography and complex geological condition, less occupation of space and low total cost. However, the construction and research of branched tunnel are still at the preliminarily stage, especially devoid of systematic and comprehensive research, which led to lack of guideline for design and construction in engineering practice.Based on the Baziling branched tunnel of Hurongxi highway which is being constructed, this thesis involves the means of field monitoring and numerical simulation, focuses on the construction method, blast vibration and thickness of mid-rock, brings forward feasible technical measures to guarantee the long-term stability of this project. The research achievement can render service for design and construction of branched tunnels.In this thesis, the methods and contents of field monitoring, layout and locations of monitoring items are detailedly expatiated. The rock mass deformation including deep displacement, circumjacent convergence and vault settlement, primary support force and final lining force are analyzed according to the monitoring data. This work will bring two aspects of merit. For one thing, as construction monitoring, it can guarantee the safety of Baziling branched tunnel and provide helpful reference to check the rationality of design. For another, it can give other branched tunnels that are being constructed or will be constructed beneficial advices owing to the receipt of rules from this project.In the next place, the blast vibration numerical simulation of big-arch section, double-arch section and small spacing section is carried out with FLAC^3D. The distribution laws of stress, displacement and velocity field based on different quantity of explosive and different blast position are obtained. In virtue of peak particle velocity criteria, the maximal single-stage initiating explosive under different classifications of rock mass and different excavation methods is proposed更多还原