超大直径双线泥水盾构施工的三维数值模拟

以上海长江西路隧道工程为背景,基于适合软土的修正剑桥模型并综合考虑盾构开挖、开挖面泥水压力、盾尾注浆以及盾壳刚度和坡度等因素,建立单台超大直径(=15.43m)泥水盾构往返推进的三维有限元模型。分析不同施工步、不同泥水压力下北线盾构施工对地表沉降以及新建南线隧道的横向位移影响。通过数据分析发现,盾构返回推进时的地表位移规律明显区别于单条隧道施工的情况;盾构的反向推进会造成已建隧道管片的挤压变形以及顺指针的旋转;返回推进时,泥水压力的不同取值对已建隧道的横向位移影响显著。根据数值分析结果提出相应的施工建议:盾构返回施工时适当减小泥水压力;密切监控盾构返回推进时切口断面后1倍刀盘直径范围内已建隧道管片的变形量。

Three dimensional simulation of super-large double-line slurry shield tunneling

Based on the background of Shanghai West Changjiang Road slurry shield tunneling project,a three-dimensional FEM study with modified Cam-Clay model is carried out to simulate the round trip tunneling of single super-large(=15.43m) slurry shield.This model takes into account several relevant components of tunneling process(the construction step,slurry pressure,tail void grouting,shield body stiffness and slope) and investigates the effects on the lateral displacement of the newly constructed tunnel when the shield advances back.Several conclusions are made by data analysis: the pattern of ground settlement is different from single tunnel construction when the shield tunnels backward;shielding of the second tunnel causes compressive deformation and clockwise rotation of the existed one;differences in slurry pressure significantly affect the lateral displacement of the existed tunnel.On the bases of simulation results,two construction proposals are made: reduce the slurry pressure when the shield tunnels backward,and the deformation of existed tunnel should be closely monitored especially in the range of 1 diameter of cutter head behind the cutting face.