盾构下穿高速铁路隧道沉降变形控制标准研究

Study on settlements control standards for shield tunneling beneath high-speed railway tunnels

针对新建盾构下穿高速铁路隧道变形控制难的问题,以石家庄地铁4、5号线以及北京地铁8号线等3个典型的穿越高铁工程为依托,研究下穿高铁隧道沉降变形控制标准.首先,利用有限元软件Midas GTS NX构建精细化的无砟轨道-隧道三维有限元模型,计算盾构下穿整体现浇隧道、盾构法隧道及U型槽段引起的不同沉降工况下的结构内力值,得出满足裂缝宽度限值的结构允许变形值,并且计算了满足规范限值要求的CRTSⅡ型和CRTSⅢ型轨道结构的允许变形值.然后,利用Abaqus软件构建车轨耦合动力模型,计算不同列车速度和沉降工况下车辆的安全性和舒适性指标,得出轨道高低不平顺允许值.最后,汇总各结构的允许变形值,给出结构沉降变形控制标准.研究结果表明:从结构裂缝宽度限值、轨道10 m弦长高低偏差限值和动力学最敏感指标限值方面计算的既有结构允许变形值能够作为盾构下穿高铁隧道沉降变形的控制标准,可作为现行规范的支撑与补充.研究成果可为类似风险大、要求较严的高速铁路穿越工程项目提供隧道及轨道变形控制值参考.

Addressing the challenging issue of deformation control in newly constructed shield tunnels beneath high-speed railway tunnels,baced on three typical high-speed railway crossing projects of Shi⁃jiazhuang Metro Line 4,Line 5,and Beijing Metro Line 8,this study investigates the standards for controlling settlements and deformations beneath high-speed railway tunnels.Firstly,a refined ballast⁃less track-tunnel three-dimensional finite element model is constructed using the finite element soft⁃ware Midas GTS NX.The model calculates the structural internal forces under various settlement con⁃ditions induced by shield tunneling beneath cast-in-place tunnel,shield tunneling and U-groove sec⁃tion.It derives the allowable deformation values of structures meeting crack width limits and calculates the allowable deformation values of CRTSⅡand CRTSⅢtrack structures meeting specification lim⁃its.Subsequently,Abaqus software is employed to build a coupled vehicle-rail dynamic model,com⁃puting safety and comfort indexes of vehicles under different train speeds and settlement conditions,and deriving allowable values for track height and smoothness.Finally,the study consolidates the al⁃lowable deformation values of each structure and presents standards for controlling structural settle⁃ment and deformation.Results indicate that the allowable deformation values of existing structures,computed based on limits of structural crack width,10 m chord length track height deviation,and dy⁃namics’most sensitive indexes,can serve as standards for settlement and deformation control of shield tunnels beneath high-speed railway tunnels.These standards can complement existing specifica⁃tions and provide valuable references for similar high-risk,high-demand projects involving high-speed railway crossings.