摘要
结合目前公路隧道洞口段支护结构加强设计存在的问题,文章从洞口段与洞身浅埋段的围岩特性、荷载作用特点入手,基于超前管棚、初期支护、二次衬砌的作用机理,分析了支护结构在不同围岩条件下的作用特点,给出了洞口加强段和洞身浅埋段衬砌设计的合理化建议。主要得到以下结论:(1)洞口段围岩破碎,自稳能力差,超前支护为围岩早期稳定提供条件,初期支护为主要承载结构,二次衬砌承担部分荷载并提供一定的安全储备;由于洞口段衬砌上覆荷载较洞身浅埋段小得多,不宜加强二次衬砌,因此洞口加强段衬砌设计应以加强超前支护与初期支护为主。(2)洞身浅埋段围岩较完整,有一定的自稳能力,二次衬砌为主要承载结构,初期支护主要发挥与围岩粘附的协同作用;洞身浅埋段衬砌设计应以加强二次衬砌为主,并要控制施作时机。
In light of the existing problems regarding the reinforcement design of support at the portal sections of highway tunnels, and based on the characteristics of surrounding rock and its loading at the portal and shallow-buried tunnel sections, this paper analyzes supporting features under different rock conditions by considering the action mechanisms of pipe-roof support, primary support, and secondary linings, and gives relevant suggestions for the above two sections. The results show that due to fractured surrounding rock and its poor self-stability at the portal section, the advance support plays an important role in enhancing the early stability of the rock, the primary support serves as the main bearing structure, and the secondary lining can be used to share part of load with a certain safety reserve. Thus, for the portal section it is better to strengthen the advance support and the primary support instead of the secondary lining, since the loads at the portal section are less than that at the shallow-buried section. Additionally, because of the intact surrounding rock and its certain self-stability at the shallow-buried section, the secondary lining serves as the main bearing structure and the primary support gives play to adhesion for better coordination between the surrounding rock and the support structure. Consequently, it is better to strengthen the secondary lining at the shallow-buried section and choose the best time for installation.
出处
《现代隧道技术》
EI
北大核心
2014年第6期12-18,共7页
Modern Tunnelling Technology
关键词
公路隧道
洞口加强段
支护结构
荷载特点
作用机理
Highway tunnel Reinforcement at the portal section Support structure Loading characteristics Ac-tion mechanism
