基坑开挖诱发下卧既有隧道隆起变形解析解  

Analytical solution on uplift deflection of underlying existing tunnel induced by foundation pit excavation

作　　者：冯国辉 陈光仔 张迪[4] 孙峰[4] 万鹏 李雨杰 杨颖 徐长节[1,2,6,7] FENG Guohui;CHEN Guangzai;ZHANG Di;SUN Feng;WAN Peng;LI Yujie;YANG Ying;XU Changjie(Research Center of Coastal and Urban Geotechnical Engineering,Zhejiang University,Hangzhou 310058,China;Center for Balance Architecture,Zhejiang University,Hangzhou 310028,China;Department of Civil Engineering,Hangzhou City University,Hangzhou 310015,China;China Railyway Siyuan Survey and Design Group Co.,Ltd.,Wuhan 430061,China;School of Computer Science and Technology,Anhui University,Hefei 230601,China;Jiangxi Key Laboratory of Infrastructure Safety Control in Geotechnical Engineering,East China Jiaotong University,Nanchang 330013,China;State Key Laboratory of Performance Monitoring Protecting of Rail Transit Infrastructure,East China Jiaotong University,Nanchang 330013,China)

机构地区：[1]浙江大学滨海和城市岩土工程研究中心,浙江杭州310058 [2]浙江大学平衡建筑研究中心,浙江杭州310028 [3]浙大城市学院土木工程系,浙江杭州310015 [4]中铁第四勘察设计院集团有限公司,湖北武汉430061 [5]安徽大学计算机科学与技术学院,安徽合肥230601 [6]华东交通大学江西省岩土工程基础设施安全与控制重点实验室,江西南昌330013 [7]华东交通大学轨道交通基础设施性能监测与保障国家重点实验室,江西南昌330013

出　　处：《铁道科学与工程学报》2023年第10期3908-3917,共10页Journal of Railway Science and Engineering

基　　金：国家自然科学基金资助项目(52238009,U1934208,51878276,52008373);国家杰出青年科学基金资助项目(51725802);浙江省自然科学基金资助项目(LHZ19E080001);江西省自然科学基金资助项目(20223BBG71018);浙江大学平衡建筑研究中心配套资金资助(20203512-10C);南昌轨道交通集团科研项目(2019HGKYB002)。

摘　　要：基坑开挖会引起周边土体产生自由位移,进而对下卧隧道产生较大的安全隐患。目前,现有的理论方法大多数是将既有隧道简化成欧拉梁放置在单参数Winkler和双参数Pasternak地基模型上,未考虑到隧道剪切变形以及土体应力扩散效应对既有隧道受力变形的影响。基于此,提出一种可预测基坑开挖诱发下卧隧道隆起变形的理论方法。采用Mindlin解获得基坑开挖引起既有隧道轴线处的土体自由位移,把土体自由位移转化成附加应力施加在既有隧道上,引入Fourier函数方程将附加应力转化成Fourier级数形式,将既有隧道假定为放置在三参数Kerr地基上的铁木辛柯梁,结合隧道边界条件获得隧道变形响应解析。工程案例分析结果表明:与该方法退化解比较,该方法计算结果更符合有限元数据;与既有文献理论解比较,该模型预测值与现场监测数值较为吻合。敏感因素分析可得:随着剪切刚度增强,隧道抵抗变形的能力逐渐增大,隧道的隆起变形也会不断减小,隧道所受弯矩和剪力反而会不断增大。随着土体弹性模量以及隧道轴线埋置深度增加,既有隧道受到的附加应力逐渐减小,隧道的变形以及所受弯矩和剪力均会不断减小。该方法退化的欧拉梁解析会进一步提高隧道抵抗变形能力,使得隧道变形减小,但会导致内力增大。该方法退化的Pasternak地基模型会高估既有隧道受力变形的影响。The excavation of the foundation could cause free displacement of the surrounding soil,which in turn could create a greater safety hazard to the tunnel underneath.The majority of the existing theoretical methods simplify the existing tunnel as an Euler-Bernoulli beam lying on single-parameter Winkler and two-parameter Pasternak foundation models,without considering the effects of tunnel shear deformation and soil stress diffusion on the behavior of existing tunnels.Based on this deficiency,a theoretical method for predicting uplift deflection of underlying tunnel due to excavation unloading was proposed.First,the soil-free displacement at the centerline of tunnel induced by excavation could be calculated by Mindlin solution.Then the soil-free displacement was put upon tunnel by taking the Fourier function into consideration,and the additional loading could be transformed into the Fourier series form to assume the existing tunnel as a Timoshenko beam resisting on a three-parameter Kerr foundation.The analysis of tunnel deflection response based on the boundary conditions could be captured.The results of engineering case show that compared with the degraded solutions based on the proposed method,the solution by the proposed method is more in accordance with the FEM data.Compared with the theoretical result of the existing literature,the prediction solutions of this model are in line with the site monitoring data.The analysis of sensitive factors indicates that as the shearing rigidity of the tunnel increases,the ability for resisting deformation of tunnel gradually increases and the tunnel uplift deformation would increase but the bending moment and shear force would reduce.As the soil flexibility modulus and tunnel centerline depth increase,the additional stress on the existing tunnel is gradually reduced and the tunnel deflection and bending moment and shear force would reduce.The degradable Euler-Bernoulli beam solution given by this method would further improve the tunnel deformation capacity,resulting in a red

关 键 词：开挖卸载 FOURIER级数 铁木辛柯梁 Kerr地基 隆起变形 

分 类 号：TU443[建筑科学—岩土工程]