饱和粉细砂地层隧道围岩塌落机理及施工控制研究

Study on the collapse mechanism and construction control of saturated fine sand tunnel

针对宝峰隧道深埋穿越饱和粉细砂段施工过程中出现洞内流砂、地表陷坑及高速路面下沉现象,采用颗粒离散元分析方法,建立了浅、深埋条件下饱和粉细砂围岩受力分析计算模型,研究了饱和粉细砂地层隧道围岩塌落破坏过程,结果表明无论深浅埋,隧道开挖后都无法形成有效的塌落拱。超前改良加固围岩,增加隧道周边围岩的承载能力,提高围岩黏聚力,是确保该地层围岩稳定的最有效手段。在此基础上,提出了"拱部双层超前旋喷咬合桩+掌子面正面旋喷桩加固+边墙单层超前旋喷咬合桩+加强衬砌结构"饱和粉细砂地层围岩加固及施工控制措施,可为类似工程提供有益参考。

This paper studied the failure process of surrounding rock mass in saturated silty sand tunnel, showing that no matter the deep or shallow burial, the collapsed tunnel can not form an effective arch. Improving the surrounding rock, enhancing the bearing capacity and the cohesion of rock are the most effective way to ensure the stability of surrounding rock. Based on this, the author puts forward the reinforcement and construction control measures for the surrounding rock characterized by saturated fne sand. The "Arch double-layer advanced rotary spray occlusive pile + Side wall singlelayer advanced rotary spray occlusive pile + Reinforcement of positive jet grouting pile on palm face + Strengthening lining structure", can be served as effective reference for similar projects.