基于非连续地基梁模型的基坑开挖诱发下卧盾构隧道变形分析  

Deformation analysis of underlying shield tunnel induced by foundation pit excavation based on discontinuous foundation beam model

作　　者：黄明华 钟煜轩 陆锦斌 王克平 HUANG Ming-hua;ZHONG Yu-xuan;LU Jin-bin;WANG Ke-ping(School of Civil Engineering,Hunan University,Changsha,Hunan 410082,China)

机构地区：[1]湖南大学土木工程学院,湖南长沙410082

出　　处：《岩土力学》2025年第2期492-504,共13页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.52378339);湖南省自然科学基金(No.2023JJ30135);长沙市自然科学基金(No.kq2208031)。

摘　　要：分析基坑开挖所诱发的下卧盾构隧道变形对评估其安全状态具有重要意义,但已有研究通常将下卧盾构隧道等效为均质连续梁,难以反映其环间接头的影响。为此,引入考虑环间接头转动和错台位移影响的非连续地基梁模型对基坑开挖所诱发的下卧盾构隧道变形进行分析。首先,根据Mindlin解导出基坑开挖卸载作用在下卧盾构隧道轴线处所产生竖向附加荷载的理论表达式;其次,基于非连续地基梁模型,推导竖向附加荷载作用下盾构隧道环段的竖向位移控制微分方程及环间接头的内力连续性条件与变形关系;最后,利用有限差分法建立下卧盾构隧道竖向位移的理论计算方法,并通过实际工程案例进行对比验证,分析接头转动刚度和剪切刚度、地基反力系数、基坑开挖深度以及基坑与盾构隧道水平间距等参数的影响。结果表明:基于非连续地基梁模型所得到的盾构隧道竖向位移与实测值具有较好的一致性,分布曲线在环段内光滑、在环间接头处有突变,反映了环间接头的转动和错台位移特性;随着接头转动刚度的增加,环段接头转角位移会逐渐减小,环间错台量则会逐渐增加;而接头剪切刚度越大,盾构隧道竖向位移与环间错台量则会越小;地基反力系数以及隧道与基坑间距的增大,基坑开挖深度的减小,均会使得盾构隧道竖向位移与环间错台量减小,其弯矩与剪力亦可得到有效控制。Analyzing the deformation behavior of underlying shield tunnels induced by foundation pit excavation is crucial for assessing their safety.However,existing studies usually treat underlying shield tunnels as homogeneous continuous beams,which makes it difficult to reflect the influence of segment joints.This study introduces a discontinuous foundation beam model that accounts for rotational deformation and longitudinal dislocation at segment joints to investigate the deformation behavior of underlying shield tunnel induced by foundation pit excavation.Firstly,a theoretical expression for calculating vertical additional stresses caused by the unloading effect of foundation pit excavation is derived using the Mindlin solution,and computation positions set along the longitudinal direction of underlying shield tunnel.Secondly,a governing differential equation for vertical displacement induced by additional vertical stresses is developed using the discontinuous foundation beam model,along with the derivation of continuity conditions for internal forces and deformation at segment joints.Finally,the finite difference method is employed to develop a theoretical solution and calculation approach for the vertical displacement and internal forces of the underlying shield tunnel.A case study is presented to verify the reliability of the develop solution and calculation method.The influences of rotational stiffness and shear stiffness of segment joints,foundation reaction coefficient,excavation depth,and horizontal spacing between foundation pit and shield tunnel are illustrated and discussed in detail.The results indicate that the calculated vertical displacements of the shield tunnel based on discontinuous foundation beam model align well with the measured data.The corresponding distribution curves are smooth within segments but change suddenly at joints,effectively reflecting rotational deformation and longitudinal dislocation at segment joints.As the rotational stiffness of segment joint increases,the rotational deformatio

关 键 词：基坑开挖 下卧盾构隧道 非连续地基梁模型 环段接头 竖向变形 

分 类 号：TU476[建筑科学—结构工程]