引汉济渭秦岭隧洞围岩变形规律与拱架受力特征研究

Deformations of surrounding rock and stress characteristics of steel arch of Hanjiang-Weihe River water diversion tunnel

引汉济渭输水隧洞地应力高、岩石强度高、开挖扰动强、地质条件复杂,在开挖过程中有时出现支护结构失稳、失效,严重威胁施工人员人身和设备财产安全。为了更准确地了解现场支护结构的安全状态,依托引汉济渭秦岭隧洞TBM施工段岭北工程,在典型围岩洞段监测围岩收敛变形及钢拱架内外翼缘受力,分析其分布特征和变化规律,同时根据围岩破坏特征,探讨围岩破坏机制。分析结果表明:隧洞围岩变形分为3个阶段,即急剧变形期、快速变形期和缓慢变形期,变形主要集中在开挖60 h内,其变形量约占总变形量的45%左右;初期支护钢拱架应力受力特征较为复杂,钢拱架应力不对称,总体表现为以受压为主,结合拱架轴力和弯矩分析,可有效判断拱架的安全状态。

The Hanjiang-Weihe River water diversion tunnel has high in-situ stress,high rock strength,strong excavation disturbance and complex geological conditions.During the excavation process,the supporting structures sometimes become unstable and fail,which seriously threatens the safety of workers,equipments and properties.To better understand the safety state of supporting structures,for the Lingbei project of the Qinling Tunnel,the convergent deformations of surrounding rock and the stress on the inner and outer flanges of the steel arch are monitored to analyze their distribution characteristics and evolution process.The analysis results show that the deformations of the surrounding rock can be divided into three stages,rapid deformation period,deformation period,and slow deformation period.The deformations mainly occur within 60 hours of the excavation,accounting for approximately 45% of the total deformations.The stress characteristics of steel arch are complicated.The stress applied on the steel arch is asymmetric,and the overall performance is mainly compression.By analyzing its axial forces and bending moments,the safety state of the arch frame can be identified.