不同地质条件下盾构隧道受力变形特性研究

针对天津滨海地区盾构隧道衬砌结构，采用大型有限元软件ABAQUS建立三维地层-结构模型，考虑隧道管片材料非线性特征，利用混凝土材料的塑性损伤本构模型，研究地层和隧道结构相互作用后隧道管片结构内力分布与变形特征，以及隧道管片受拉和受压损伤情况。最后，研究不同地质条件和超载作用对隧道管片结构的影响。数值分析结果表明：隧道管环横截面变形表现为水平向外扩张、竖向压缩的特点，呈现“横鸭蛋”形状；隧道管环拱顶轴压力最小，拱腰轴压力最大；管片外侧受拉时最大弯矩位于拱腰，内侧受拉时最大弯矩位于拱顶；受拉和受压损伤分布均集中在拱底附近，其中管环受压损伤面积比受拉损伤面积大；地质条件越好，变形随轴线方向变化越均匀，轴力和弯矩、隧道结构竖向位移、横截面收敛变形，以及管环损伤面积与损伤程度越小。研究结果以期为进一步探讨隧道衬砌结构的变形性能与损伤分布提供参考。

Research on inner force and deformation characteristics of shield tunnel under different geological conditions

In order to study the lining structure of shield tunnel in Binhai district of Tianjin city, a three-dimensional strata structure model was established by the finite element software ABAQUS. Considering the nonlinear characteristics of tunnel segments material, using the plastic-damage constitutive model of concrete material, the Internal force distribution and deformation properties of tunnel segment structure after the interaction of stratum and tunnel structure, as well as the tension and compression damage of tunnel segments were studied. Finally, the influence of different geological conditions on the structure of tunnel segments was studied. The results of numerical analysis show that: The deformation of the cross section of the tunnel segment is characterized by horizontal outward expansion and vertical compression, showing the shape of “horizontal duck egg”. The axis force of the tunnel vault is the smallest and the arch waist axis force is the largest. When the outside of segment is pulled, the maximum bending moment is located in the arch waist. When the inner side of segment is pulled, the maximum bending moment is located in the vault. The distribution of tension and compression damage is concentrated in the arch bottom, and the area of the compression damage area of the segment is larger than that of the tensile damage area. The better the geological conditions, the more uniform the deformation is with the axis direction, the smaller the axial force and bending moment, the vertical displacement of the tunnel structure, the deformation of the cross section, and the damage area and damage degree of segment ring are. The research results provide reference for further discussion on deformation performance and damage distribution of tunnel lining structure.