摘要
基坑开挖将对周围土体造成应力扰动,打破地层的应力平衡状态,进而使下卧地铁隧道结构遭到不同程度的破坏。针对既有研究的不足,考虑地基土体的非均质性对作用于隧道上附加应力的影响,引入弹性层状半空间地基模型,建立基坑开挖对下卧隧道影响的两阶段分析法。采用Hankel积分变换得到作用荷载表达式,运用矩阵递推法,推导出层状地基中轴对称垂直荷载作用下土体竖向附加应力解。在此基础上,基于Winkler-Pasternak双参数地基模型将既有隧道视为Euler-Bernoulli长梁,建立隧道变形后的挠度平衡微分方程,采用有限差分法将方程简化并获得隧道纵向变形解析解。通过与Winkler地基模型对比,发现Winkler-Pasternak模型能体现地基弹簧的相互作用,计算结果更精确,而Winkler模型明显高估隧道纵向变形。结合有限元数值模拟和工程实例进行分析,证实所提出方法的有效性。研究成果为准确预测下卧隧道在基坑开挖卸荷作用下的变形提供了一定理论支撑。
The excavation of foundation pit will change ground stress state,which may cause a series of adverse impacts on the underlying metro tunnel.The elastic layered soils model is put forward to considering the influence of the additional stress on the tunnel due to the soil non-homogeneous characters.In order to simplify research process,two-stage method is presented for predicting the behaviors of the underlying metro tunnel associated with foundation pit.First,the load expression is obtained by using the Hankel integral transformation,and then the additional stress of soils under vertical load of axisymmetric in layered soils can be obtained through the tranferring matrix method.Second,the existing tunnel is regarded as an Euler-Bernoulli beam resting on the Winkler-Pasternak foundation model.Meanwhile,equilibrium differential equations of beam based on the Winkler-Pasternak model theory can be established.Furthermore,analytical solutions of the longitudinal deformation of the tunnel are obtained by using the finite difference method.The numerical solutions of the Winkler-Pasternak model theory are more accurate than the Winkler model theory because the Winkler-Pasternak model can reflect the interaction between foundation springs.Finally,the results of the proposed method are compared with numerical simulation and measured data,which verifies the effectiveness of the proposed method.It can provide a theoretical support for predicting the deformation of underlying metro tunnel accurately due to the unloading of foundation pit excavation.
作者
江杰
邱居涛
欧孝夺
龙团元
侯凯文
赖增任
JIANG Jie;QIU Jutao;OU Xiaoduo;LONG Tuanyuan;HOU Kaiwen;LAI Zengren(College of Civil Engineering and Architecture,Guangxi University,Nanning 530004,China;Key Laboratory of Disaster Prevention and Structural Safety of Ministry of Education,Guangxi University,Nanning 530004,China;Guangxi Key Laboratory of Disaster Prevention and Engineering Safety,Guangxi University,Nanning 530004,China)
出处
《铁道学报》
EI
CAS
CSCD
北大核心
2021年第10期118-126,共9页
Journal of the China Railway Society
基金
国家自然科学基金(52068004)
广西自然科学基金(2018JJA160134)
广西重点研发计划(AB19245018)。
关键词
基坑开挖
层状地基
附加应力
地铁隧道
两阶段分析法
纵向变形
foundation pit excavation
layered soils
additional stress
metro tunnel
two-stage method
longitudinal deformation
作者简介
第一作者:江杰(1979-),男,湖北麻城人,研究员,博士。E-mail:765068591@qq.com;通信作者:欧孝夺(1970-),男,广西来宾人,教授,博士。E-mail:ouxiaoduo@163.com。
