高海拔板岩隧道大变形特性及控制技术研究

Study on Large Deformation Characteristics and Construction Control Technology in High Altitude Slate Tunnel

依托四川省省道217线海子山隧道工程,综合采用工程总结、地质分析、数值分析和现场测试等方法对高海拔软弱板岩地层大变形破坏特征、主要因素和对策措施进行了探讨。研究主要成果:总结了海子山隧道具有变形量大、受地下水影响显著、挤压变形、变形持续时间长和以拱部变形为主的板岩大变形破坏特征,大变形多发生在掌子面附近及上台阶拱部、拱腰及拱脚位置,地下水发育段变形具有突发性;指出了导致海子山隧道大变形的主要因素是板岩岩性、地下水作用及因高海拔作业效率低使初期支护不能及时封闭等;通过加强地质工作、优化设计参数(增强支护刚度、多重支护、加大预留变形量)、选择合理工法、加强施工管理等措施提出了隧道大变形控制技术,确保了整座隧道的顺利施工和贯通,可作为类似工程的借鉴。

Based on the Haizishan tunnel construction of Sichuan Provincial Highway 217,the characteristics,main factors and countermeasures of large deformation of soft slate strata at high altitude are discussed by means of engineering summary,geological analysis,numerical analysis and field test.The main conclusions are as follows:Firstly,this paper summarizes the large deformation and damage characteristics of the slate with large deformation,significant influence on groundwater,compression deformation,long deformation duration and main deformation caused by arch.Large deformation mostly occurs near the tunnel face and at the arch,waist and foot of the upper bench.And the deformation of the groundwater development section is sudden.Secondly,it is pointed out that the main factors leading to large deformation of Haizishan tunnel are slate lithology,groundwater action and the failure of closing initial support in time due to the low efficiency operation in high altitude.Lastly,through strengthening geological work,optimizing design parameters(enhancing support stiffness,multiple support and increasing reserved deformation),choosing reasonable construction methods and strengthening construction management,the large deformation control technology of the tunnel are put forward,which ensures the smooth construction and penetration of the whole tunnel and can be used as a reference for similar engineering.