摘要
盾构掘进过程中经常会遇到钢筋混凝土桩基等,通过桩基托换技术配合盾构刀盘改造使盾构具有直接破桩的能力,可为隧道线路设计提供更多的可选性与灵活性。以苏州轨道交通8号线下穿圆融桥工程为背景,先对桥梁进行加固设计计算,再采用有限差分软件FLAC3D建立三维模型,同时通过在隧道掌子面施加切削荷载来模拟真实切削情况,分析盾构切削桩基期间对既有桥梁结构变形的影响。结果表明:盾构切桩会导致桩基正上方土体隆起,地表沉降曲线由于切桩影响不再符合正态分布,最大沉降位于双隧道轴线中心附近;刀盘切断桩基后,断桩下部失去部分承载力,导致上部发生向下的位移,桥梁墩台发生向断桩中间凹陷的挠曲变形;盾构隧道左、右线之间的桩基会随着掌子面推进先后产生背离隧道方向的弯曲变形,随着掌子面距切削桩基的距离逐渐减小,桥面沉降逐渐增大,当盾构机掘进至切削桩基范围内,沉降增长变化近3倍。
In the process of shield tunnelling,reinforced concrete pile foundation is often encountered.Through the pile foundation underpinning technology and the shield cutterhead modification the shield can directly cut the pile,which can provide more options and flexibility for the tunnel route design.Based on the Suzhou Rail Transit Line 8 passing under Yuanrong Bridge,the reinforcement design of the bridge was checked and calculated firstly,and then the finite difference software FLAC3D was used to establish a three-dimensional model,and the real cutting situation was simulated by applying the cutting load on the tunnel working face to analyze the influence of the shield cutting pile foundation on the deformation of the existing bridge structure.The results show that the shield cutting pile will lead to the uplift of the soil directly above the pile foundation,the surface settlement curve doesn't conform to the normal distribution due to the influence of pile cutting,and the maximum settlement is located near the center of the double-line tunnel axis.After the cutterhead cuts off the pile foundation,the lower part of the broken pile loses part of the bearing capacity,resulting in the downward displacement of the upper part,and the deflection deformation of the bridge pier towards to the middle of the broken pile.The pile foundation between the left and right shield tunnels will successively experience bending deformation opposite to the direction of the tunnel with the advancement of the tunnel face,the settlement of bridge deck will gradually increase as the distance between the tunnel face and the cutting pile foundation gradully decreases,and the settlement growth changes nearly 3 times when the shield machine excavates to the range of the cutting pile foundation.
作者
白建军
彭凯西
吴奔
梁嘉骏
BAI Jianjun;PENG Kaixi;WU Ben;LIANG Jiajun(Urban Rail Transit Co.,Ltd,China Railway 10th Bureau Group,Guangzhou 511493;School of Rail Transit,Soochow University,Suzhou 215137)
出处
《现代隧道技术》
CSCD
北大核心
2024年第S01期445-453,共9页
Modern Tunnelling Technology
关键词
盾构切桩
桥梁变形
桥梁加固
数值分析
Shield cutting pile
Bridge deformation
Bridge reinforcement
Numerical analysis
作者简介
白建军(1987-),男,本科,高级工程师,主要从事隧道及地下工程施工技术管理工作,E-mail:564227307@qq.com;通讯作者:吴奔(1997-),男,硕土,主要从事隧道及地下工程的研究工作,E-mail:cauchybw1611@163.com.
