TBM隧道下穿交角对高速铁路隧道变形影响研究

Research on the Influence of TBM Tunnel Underpass Intersection Angle on the Deformation of High-Speed Railway Tunnels

由于隧道断面尺寸不同、施工方法不同,在不同下穿角度下,既有隧道的变形沉降规律有所不同。对于埋深较大的山岭隧道,隧道交角对既有隧道变形的影响有待进一步研究。以瓯江引水工程TBM隧道下穿既有圆岩寨高速铁路隧道工程为背景,分析不同下穿交角下既有隧道的变形规律。采用了现场监测对比数值模拟的研究方法,既有隧道采用全站仪自动化监测方案,监测下穿期间既有隧道的沉降变形;通过MIDAS GTX NX建立三维数值模型,研究了新建TBM隧道下穿交角为0°、18°、58°、78°、90°的情况下既有高速铁路隧道的变形。研究表明:既有隧道拱腰处的沉降值,先开挖段略大于后开挖段;当隧道垂直相交时,既有隧道最大沉降值相对最小,但不同交角下,既有隧道最大沉降值相差不大;既有隧道沉降沿轴线方向呈“凹槽型”分布,随着两隧道交角减小,凹槽张开程度增大,既有隧道受新建隧道施工影响的扰动区域增大,且既有隧道扰动影响范围长度与隧道叠交长度呈正相关关系。为了减小既有隧道的扰动范围,建议新建TBM隧道以大角度相交的方式穿越既有隧道。

Due to varying tunnel section sizes and construction methods,the deformation and settlement behavior of existing tunnels differ under different undercrossing angles.For mountain tunnels with large buried depth,the influence of tunnel intersection angles on the deformation of existing tunnels requires further investigation.This study focuses on the TBM tunnel of the Oujiang Diversion Project,which underpasses the existing Yuanyanzhai High-Speed Railway Tunnel,aiming to determine the deformation law of the TBM tunnel under different undercrossing angles beneath the existing high-speed railway tunnel.The study adopts a combined approach of field monitoring and comparative numerical simulation.The existing tunnel's settlement during the underpass was monitored using an automated total station system.A three-dimensional numerical model was established using MIDAS GTX NX to study the deformation law of the existing high-speed railway tunnel under the condition of the new TBM tunnel crossing angles of 0°,18°,58°,78°and 90°.The research shows that the settlement at the arch waist of the existing tunnel of the first excavation section is slightly larger than that of second the excavation section.When the tunnels intersect vertically,the maximum settlement value of the existing tunnel is relatively small.However,across different intersection angles,the variation in maximum settlement values is not significant.The settlement of the existing tunnel is distributed in a"groove"shape along the axis,and as the intersection angle decreases,the groove widens,increasing the disturbance area of the existing tunnel due to the construction of the new tunnel.The length of the disturbance area in the existing tunnel is positively correlated with the length of the tunnel overlap.In order to minimize the disturbance to the existing tunnel,it is recommended that the new TBM tunnel cross the existing tunnel at a large angle.