砂土地层深基坑开挖引起下卧隧道变形机理研究  

Study on Deformation Mechanism of the Underlying Tunnel Caused by Excavation of the Deep Foundation Pit in Sandy Stratum

作　　者：范燕波 陈丽 史江伟[1,2] 丁楚 张显 FAN Yanbo;CHEN Li;SHI Jiangwei;DING Chu;ZHANG Xian(Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering,Hohai University,Nanjing 210098;Geotechnical Research Institute,Hohai University,Nanjing 210098;Construction Engineering Quality Center Laboratory of Zhenjiang New District,Zhenjiang 212132)

机构地区：[1]河海大学岩土力学与堤坝工程教育部重点实验室,南京210098 [2]河海大学岩土工程科学研究所,南京210098 [3]镇江新区建设工程质量中心试验室,镇江212132

出　　处：《现代隧道技术》2021年第2期103-110,共8页Modern Tunnelling Technology

基　　金：国家自然科学基金(51608170).

摘　　要：深基坑开挖引起的应力释放将不可避免地引起邻近隧道的附加应力和变形。通过开展三维有限元数值分析,研究了深基坑开挖尺寸和管片接头刚度对下卧隧道三维变形的影响。利用土工离心模型试验验证了有限元计算模型和结果的合理性。在基坑中心线下,隧道隆起和横向弯曲应变随基坑开挖长度的增大而增大。当基坑开挖长度为基坑开挖深度的9倍时,隧道隆起和横向弯曲应变达到峰值;隧道纵向弯曲应变几乎接近于零。当基坑开挖长度大于9倍的开挖深度时,基坑—土—隧道的相互作用可简化为平面应变问题。若不考虑短基坑的三维效应,基坑—土—隧道的平面应变简化将严重高估隧道隆起和横向弯曲应变。隧道隆起随接头刚度的增加而逐步降低,然而隧道横向和纵向弯曲应变随接头刚度的增加而增加。因此,带接头的非连续隧道假设为连续性结构,隧道隆起会被大大低估,而隧道弯曲应变则被高估很多。he stress release caused by excavation of a deep foundation pit may inevitably cause additional stress and deformation of the adjacent tunnel.In this paper,a three-dimensional finite element numerical analysis is per⁃formed to study the influence of the excavation size of the deep foundation pit and the stiffness of segment joint on three-dimensional deformation of the underlying tunnel.Then,the geotechnical centrifugal model test is used to ver⁃ify the rationality of the finite element calculation model and relevant results.Below the centerline of the foundation pit,the uplift and lateral bending strain of the tunnel increase along with the increase of the excavation length of the foundation pit.When the excavation length of the foundation pit is 9 times of its excavation depth,the uplift and transverse bending strain of the tunnel reach the peak value while the longitudinal bending strain of the tunnel is al⁃most close to zero.When the excavation length of the foundation pit is more than 9 times of the excavation depth,the foundation pit-soil-tunnel interaction could be simplified as a plane strain issue.If the three-dimensional effect of the short foundation pit is not considered,the plane strain simplification of the foundation pit-soil-tunnel would se⁃riously lead to overestimate of the tunnel uplift and lateral bending strain.Along with the increase of the joint stiff⁃ness,the tunnel uplift gradually decreases,while the transverse and longitudinal bending strains of the tunnel in⁃crease.Therefore,if a discontinuous tunnel with joints is assumed as a continuous structure,the tunnel uplift might be greatly underestimated,while the bending strain might be largely overestimated.

关 键 词：深基坑 隧道 三维变形 接头刚度 有限元模型 

分 类 号：TU375.4[建筑科学—结构工程] U452[建筑科学—桥梁与隧道工程]