超前地质预报技术在软岩隧道施工中的应用

发布时间：2018-10-31 15:30

【摘要】：隧道工程是一个线状隐蔽工程,大多穿越复杂的地质条件,而实际施工当中又很难完全摸清隧道掌子面前方的地质情况,因此,隧道施工就存在着许多未知风险和安全隐患。为避免因盲目施工带来的风险和损失,隧洞信息化施工必须做到先探明前方地质情况后再开挖,即开挖前要预报掌子面前方的岩体状况,如有无地下水、有无破碎带等。因此,引入超前地质预报技术很有必要,开展隧道施工超前地质预报技术研究,探测掌子面前方的地质情况也迫在眉睫。本论文以四川省甘孜州乡城县洞松水电站引水隧洞工程为依托,研究了超前地质预报理论原理和应用技术,以及基于预报结果的数值模拟研究。通过将超前地质预报运用于软岩隧洞施工过程之中,建立了一套应对软岩施工常见地质灾害的地质雷达法和地质素描法相结合的预报体系,并在预报结果的基础上对软岩隧洞变形特征及支护方案的优化进行了数值模拟分析,对支护方案和开挖工法进行优化。研究得出：在超前地质预报技术的实际应用中,验证了地质雷达超前地质预报技术的精确性,预报准确率达80%。在隧洞超前地质预报中,如果发现前方存在软弱破碎带或者富水带,那么该段围岩极易发生大变形。基于上述在本工程中的实际应用成果利用FLAC3D数值模拟技术对软岩变形展开研究,对本工程软岩变形发生的规律和变形特征有了进一步的认识,得出了软岩变形的一般规律,隧洞埋深、侧压力系数越大围岩变形也越大；围岩强度越大围岩变形量越小；开挖工法模拟分析得出对于本工程,台阶法较全断面法适合；钢支撑在隧底采用曲线封闭较直线封闭能更有效控制围岩变形；二衬参与受力时,承受10%外荷载的情况下较为经济、合理。
[Abstract]:Tunnel engineering is a linear hidden project, mostly through complex geological conditions, but it is difficult to fully understand the geological situation in front of the tunnel face in the actual construction. Therefore, there are many unknown risks and security risks in tunnel construction. In order to avoid the risk and loss caused by blind construction, the tunnel information construction must find out the geological conditions in front of tunnel before excavation, that is to say, it is necessary to forecast the rock mass condition in front of the face before excavation, such as whether there is groundwater or not, whether there is a broken zone and so on. Therefore, it is necessary to introduce the advanced geological prediction technology, and it is urgent to study the advanced geological prediction technology in tunnel construction and to detect the geological situation in front of the face of the tunnel. Based on the diversion tunnel project of Dongsong Hydropower Station in Xiangcheng County, Ganzi Prefecture, Sichuan Province, this paper studies the theory principle and application technology of advanced geological prediction, and the numerical simulation research based on forecast results. By applying the advanced geological forecast to the construction process of soft rock tunnel, a set of forecasting system combining geological radar method and geological sketch method to deal with the common geological hazards in soft rock construction is established. Based on the prediction results, the deformation characteristics of soft rock tunnel and the optimization of supporting scheme are simulated and analyzed, and the support scheme and excavation method are optimized. It is concluded that in the practical application of the advanced geological prediction technology, the accuracy of the geological prediction technology of the geological radar is verified, and the accuracy of the prediction is up to 80%. In the advanced geological prediction of the tunnel, if there is a weak broken zone or a water-rich zone in front of the tunnel, the surrounding rock of this section is prone to large deformation. Based on the above practical application results in this project, the soft rock deformation is studied by using FLAC3D numerical simulation technology, and the rules and characteristics of soft rock deformation are further understood, and the general rules of soft rock deformation are obtained. The deeper the tunnel is, the larger the lateral pressure coefficient is, and the larger the deformation of surrounding rock is. The larger the strength of surrounding rock is, the smaller the deformation of surrounding rock is; the simulation analysis of excavation method shows that the step method is more suitable than the full section method for this project, and the steel bracing can control the deformation of surrounding rock more effectively by using curve closure than straight line closing at the bottom of tunnel. When the second liner takes part in the force, it is more economical and reasonable to bear 10% external load.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U452.11;U455

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