摘要
为探明对接距离对海底大直径盾构开挖面失稳机制及规律的影响,依托甬舟铁路金塘海底盾构隧道工程,建立考虑渗流的盾构隧道对接有限元模型,研究对接距离L对开挖面失稳机制以及极限支护压力的影响,并基于极限平衡法建立考虑渗流的盾构近距离对接开挖面极限支护压力理论模型。随着对接距离的增大,开挖面失稳形状和极限支护压力的变化可分为3个阶段。1)快速增长阶段(0<L/D≤0.4)(D为隧道直径):该阶段与单个隧道工况区别最明显,失稳区域由楔形体与仓筒组成;此时受对接隧道的阻碍作用最大,且开挖面附近水头场变化剧烈,渗流力占据主要部分。2)缓慢增长阶段(0.4<L/D≤0.7):失稳区域由对数螺旋体与仓筒组成,此时对接隧道的阻碍作用减小,因此极限支护压力在该阶段受对接距离的影响减小,增长缓慢。3)趋于平缓阶段(0.7<L/D≤1.5):失稳区域由对数螺旋体与倒棱台组成,此阶段对接隧道的阻碍作用可忽略不计,极限支护压力、失稳区域形状与非对接情况相近,可视为单个隧道工况。建立的理论模型得出的结果与数值模拟的结果接近,两者误差在10%以内,验证了该模型的可行性。
Herein,a case study is conducted on the Jintang subsea shield tunnel project of the Ningbo-Zhoushan railway to investigate the effect of docking distance on the instability mechanism and pattern of the excavation face for a large-diameter subsea shield.A finite element model of shield tunnel docking considering seepage is developed.Then,the effect of the docking distance(L)on the instability mechanism of the excavation face and ultimate support pressure is examined.A theoretical model for determining the ultimate support pressure for shield close-distance docking is established using the limit equilibrium method and considering seepage.As the docking distance increases,the shape variation of the excavation face and variation of the ultimate support pressure can be divided into three stages.(1)The rapid growth stage(0<L/D≤0.4)(D represents the tunnel diameter):the difference between the condition of this stage and a single tunnel working condition is the most obvious,and the instability zone comprises wedge bodies and silos.At this stage,the docking tunnel causes maximum inhibition,resulting in significant changes in the waterhead field near the excavation face,with the seepage force playing a dominant role.(2)The slow growth stage(0.4<L/D≤0.7):the instability zone comprises logarithmic spirochetes and silos.At this stage,the reduction in the inhibition caused by the docking tunnel leads to a decrease in the influence of the ultimate support pressure on the docking distance and the growth of the ultimate support pressure occurs at a low rate.(3)The gentle growth stage(0.7<L/D≤1.5):the instability zone comprises logarithmic spirochetes and chamfers.At this stage,the inhibition caused by the docking tunnel can be ignored and the ultimate support pressure and instability-zone shape are comparable to those without docking conditions,which can be considered as a single tunnel working condition.The results obtained from the established theoretical model are close to those obtained by numerical simulations,with an error within 10%,thereby confirming model feasibility.
作者
陈一凡
沈翔
陈湘生
CHEN Yifan;SHEN Xiang;CHEN Xiangsheng(State Key Laboratory of Intelligent Geotechnics and Tunnelling(Shenzhen University),Shenzhen 518060,Guangdong,China;College of Civil and Transportation Engineering,Shenzhen University,Shenzhen 518060,Guangdong,China;Key Laboratory for Resilient Infrastructures of Coastal Cities(Shenzhen University),the Ministry of Education,Shenzhen University,Shenzhen 518060,Guangdong,China)
出处
《隧道建设（中英文）》
CSCD
北大核心
2024年第4期712-723,共12页
Tunnel Construction
基金
广东省自然科学基金(2023A1515010060)
国家自然科学基金(52378404)。
关键词
海底隧道
大直径盾构
对接工程
开挖面失稳
理论模型
subsea tunnel
large-diameter shield
docking engineering
excavation face instability
theoretical model
