摘要
针对基坑开挖旁侧盾构隧道结构横向受力和变形规律,提出了一种考虑围护结构变形影响的盾构隧道横向受力理论计算方法,并通过某实际工程三维有限元计算结果和干砂地层隧道旁侧基坑开挖离心模型试验结果,验证了隧道径向附加荷载理论计算方法的可靠性。结合该工程获取的围护桩水平位移、地表沉降、隧道变形和应变现场实测数据,探究了隧道横向受力-变形-内力之间的关联机制。结果表明:(1)隧道初始径向荷载呈“葫芦形”对称分布,侧方开挖引起隧道近基坑侧和拱顶外荷载减小,而远基坑侧和拱底外荷载增大,这与开挖引起的自由场地层位移和隧道位移相对大小有关,水平和竖向不均衡荷载由隧道纵向差异变形引起的环间剪切力平衡。(2)隧道椭圆形变形、朝基底方向的顺时针旋转角度和正负弯矩值随开挖不断增大。(3)隧道环向弯矩分布与螺栓相对位置关系密切相关,研究断面处近基坑侧拱腰附近存在螺栓,其将承担更多的环向拉应力;远基坑侧拱腰附近为混凝土管片,环向拉应力主要由管片承担,从而使得研究断面处隧道管片最大环向弯矩发生在远基坑侧拱腰位置。
To investigate its transverse forces and deformations subjected to lateral excavation,a theoretical approach for estimating the transverse forces of a shield tunnel considering the influences of deflections of retaining wall proposed.The calculated radial additional loads on the tunnel is compared with the results of three-dimensional finite element analysis of a case history and centrifuge modeling of excavation effects on a nearby existing tunnel in dry sand,which verifies the reliability of this approach.Based on the measured pile deflections,ground settlements,tunnel deformations and structural strains from this case history,the interaction mechanisms of the transverse forces,deformations and internal forces of the tunnel are analyzed.The results show that:(1) The initial radial loads on the tunnel are symmetrically distributed in a “gourd shape”.The lateral excavation results in the decrease in the loads on the tunnel crown and right springline near excavation,while the loads on the tunnel invert and left springline away from excavation increase.This phenomenon is related to the relative values of the free-field ground displacements and measured tunnel displacements caused by excavation.The horizontal and vertical unbalanced loads are balanced by the shear force between neighboring rings caused by longitudinal differential deformations of the tunnel.(2) The elliptical deformations,clockwise rotations and bending moments of the tunnel all increase as the excavation proceeds.(3) The distribution of the circumferential bending moment of the tunnel is closely related to the relative position of the bolts.There are bolts near the right tunnel springline closer to the excavation at the investigated cross section,which bear more circumferential tension stress.In comparison,there are no bolts adjacent to the left tunnel away from the excavation,and thus the circumferential tension stress is mainly undertaken by the segments.Hence,the maximum circumferential bending moment of the tunnel at the investigated cross section occurs at the left springline.
作者
陈仁朋
刘慕淳
孟凡衍
李忠超
吴怀娜
程红战
CHEN Renpeng;LIU Muchun;MENG Fanyan;LI Zhongchao;WU Huaina;CHENG Hongzhan(College of Civil Engineering,Hunan University,Changsha 410082,China;Key Laboratory of Building Safety and Energy Efficiency of Ministry of Education,Hunan University,Changsha 410082,China;Wuhan Municipal Construction Group Company Limited,Wuhan 430023,China)
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2023年第1期24-32,I0003,共10页
Chinese Journal of Geotechnical Engineering
基金
国家自然科学基金项目(52090082,51938005)
博士后科学基金面上项目(2020M672489)
武汉市市政建设集团有限公司隧道工程公司科研课题:湖湘高层次人才聚集工程创新团队项目(2019RS1030)。
关键词
深基坑
旁侧盾构隧道
横向受力
变形
弯矩
deep excavation
lateral shield tunnel
circumferential force
deformation
bending moment
