某隧道初期支护变形及中空锚杆注浆效果分析

Analysis on the deformation of initial support and hollow bolt grouting effect of surrounding rock in a tunnel

以四川某隧道为研究对象,结合现场地质调研、空心包体地应力测试、初支与围岩接触压力监测等分析手段,对初期支护变形破坏的原因进行分析。分析结果表明:初支变形破坏主要是由地表水下渗、不利地应力条件、地层岩性等因素造成。同时采用FLAC3D,分析开挖后隧道上部粉砂质泥岩夹层对拱顶变形的影响,以及中空锚杆注浆前后初支受力变形情况。模拟结果表明:最大竖向位移及压应力出现在拱顶区域,且位移随着夹层距离的增加而减小,在6.5 m时出现陡降,最大水平位移在右拱腰处;锚杆注浆后拱顶位移减小约10%,边墙位移减少约4%。本文可为类似工程变形破坏原因分析及施工处治方法选择方面提供参考。

A tunnel in Sichuan as the research object, this paper uses field reconnaissance,geological condition analysis,the ground stress detection, wits stress surveying of the steel arch and other analysis methods, analyzing the reasons of initial support＇ s deformation and failure. Analysis results show that initial support deformation and failure is mainly by water infiltration, adverse stress conditions, formation lithology and the larger surrounding rock pressure factors. The Flac3d simulates the influence of silty mudstone interlayer on the deformation of tunnel after excavation and the effect of hollow bolt grouting. The simulation results show that the maximum vertical displacement and compressive stress appears in the vault area, the crown displacement with the interlayer and excavation tunnel spacing increases gradually decreases, which is the biggest change in the distance to 6.5 m. The maximum horizontal displacement occurs at the right arch waist, through the analysis of deformation condition of grouting, it is found that the vertical displacement decreases about 10% , sidewall constringency is reduced by about 4%. This paper can provide reference for similar projects in failure analysis and construction treatment method.