基坑开挖对下卧地铁隧道结构的扰动效应分析  

Analysis of disturbance effect of pit excavation on underlying subway tunnel structure

作　　者：王恩波[1] 昝文博 张喆[1] 王强[1] WANG Enbo;ZAN Wenbo;ZHANG Zhe;WANG Qiang(School of Civil Engineering,Shaanxi Polytechnic Institute,Xianyang 712000,China;School of Highway,Chang'an University,Xi'an 710064,China)

机构地区：[1]陕西工业职业技术学院土木工程学院,陕西咸阳712000 [2]长安大学公路学院,陕西西安710064

出　　处：《甘肃科学学报》2024年第5期16-23,共8页Journal of Gansu Sciences

基　　金：陕西省教育厅科技项目(23JK0314)。

摘　　要：为准确评估基坑开挖对正下方地铁隧道结构的扰动效应,依托某高速公路明挖基坑与地铁盾构隧道交叉工程,建立三维精细化有限元模型分析基坑开挖不同阶段对地铁隧道结构变形与受力的扰动特征,并结合现场监测结果对比验证“MJS工法+三轴水泥搅拌桩”地基加固、钻孔灌注桩联合水泥土挡墙、门式加固+抗浮板+反压箱和盆式开挖等组合加固措施的变形控制效果。结果表明:(1)基坑底部中间部位的“卸荷效应”最显著,是基坑开挖变形控制的关键部位;地铁隧道纵向中间断面的隆起变形量最大可达4.55 mm,靠近基坑开挖边缘位置的隧道结构隆起变形量一般为1~2 mm,处于基坑开挖边界以外的地铁隧道隆起变形不到1 mm;(2)受MJS工法、围护桩、立柱桩等施工扰动,基坑加固阶段地铁隧道结构产生微小隆起变形,随着后续基坑开挖的持续卸荷,地铁隧道结构隆起变形不断增大;隧道纵断面隆起变形呈对称分布,隧道横断面隆起变形呈“M”形分布,不同测线的变形曲线形态有所差别,这与隧道轴线与基坑开挖边界斜交角度有一定的关系;(3)左线、右线盾构隧道现场实测隆起变形最大值分别为5.35 mm和5.16 mm,核心影响区隧道水平收敛表现为向内收缩,非核心影响区隧道水平收敛表现为向外扩张;同时现场巡查未发现地铁隧道出现结构病害,表明采取的基坑变形控制加固措施是合理可行的。研究结果对于基坑开挖近接既有隧道结构的变形控制与加固措施的选择具有重要的参考价值。To accurately evaluate the disturbance effect of foundation pit excavation on the subway tunnel structure directly underneath,a 3D refined finite element model was established to analyze the disturbance characteristics of deformation and stress on subway tunnel structures at different stages of excavation,based on the intersection project of highway open excavation foundation pit project and a subway shield tunnel.Combined with on-site monitoring results,the deformation control effect of combined reinforcement measures such as MJS method+triaxial cement mixing pile foundation reinforcement,bored piles combined with cement retaining wall,portal reinforcement+anti-floating plate+counter-pressure box and basin excavation was verified.The results show that(1)The middle part of the pit bottom has the most significant unloading effect,which is the key part of pit excavation deformation control.The uplift deformation of the longitudinal center section of the subway tunnel can be up to 4.55 mm,the uplift deformation of the tunnel structure near the edge of the pit excavation is generally 1~2 mm,and the uplift deformation of the subway tunnel outside the boundary of the pit excavation is less than 1mm.(2)Disturbed by the MJS method,enclosure piles,column piles,etc.,the subway tunnel structure produces a small bulging deformation during the pit reinforcement stage,and the bulging deformation of the subway tunnel structure increases with the continuous unloading of the subsequent pit excavation.Tunnel longitudinal section bulge deformation is symmetrical distribution,the tunnel cross-section uplift deformation shows M-type distribution,the deformation of different lines of the deformation curve shape varies,which has relation with the tunnel axis and the pit excavation boundaries diagonal angel.(3)The maximum values of field-measured rumble deformation of the left and right line shield tunnels are 5.35 mm and 5.16 mm respectively,and the horizontal convergence of the tunnels in the core zone of influence manifests itself as

关 键 词：基坑开挖 地铁隧道 隆起变形 数值模拟 结构内力 

分 类 号：U45[建筑科学—桥梁与隧道工程]