基于多环拼装模型的盾构管片非线性承载性能及加固效应研究

Study on Nonlinear Bearing Performance and Reinforcement Effect of Shield Segments Based on Multi-ring Assembly Model

外部围压作用下管片结构的力学承载性能和破坏效应对隧道整体安全性能保障至关重要。为充分考虑实际情况下接头弹簧、接地弹簧及非线性材料因素对整体承载性能的影响以及局部加固的效果,采用多环拼装的壳-弹簧精细化管片结构模型进行分析。首先给出了基于壳-弹簧模拟和围压加载模式的计算理论。接着建立了15环精细管片结构三维有限元模型,进而对正常使用工况下的管片应力和变形分布规律进行了分析。然后针对极端荷载工况下,对衬砌管片的线性屈曲模态和非线性极限稳定承载性能进行了研究。最后考虑全部环加固和间隔环加固两种方式,针对高性能复合砂浆钢筋网(HPF)对衬砌管片极限承载性能的加固效应进行了探讨。研究表明:外部围压作用下衬砌管片呈现为类似于扁椭圆的横向整体变形形式;正常使用工况下,管片最大Von Mises应力为单轴抗压强度的0.585,最大全位移对应变形椭圆度为4.03‰,符合规范要求且承载性能良好;极端荷载工况下,荷载-位移曲线变化趋势为线性迅速增大、非线性平缓增大和趋于平缓收敛,管片极限荷载系数为3.522,具有较好的非线性稳定承载性能;HPF加固可有效提高管片的极限承载性能,间隔环加固、全部环加固后管片的极限承载力相对未加固时分别提高了约8.26%,17.80%。

The mechanical bearing performance and failure mode of lining segment structure under external confining pressure are very important for the overall safety of tunnel. In order to fully consider the influence of joint spring, grounding spring and nonlinear material factors on the overall bearing capacity and the effect of local reinforcement in practice, a multi-ring assembled shell-spring refined segment structure model is used for analysis. First, the calculation theory based on shell-spring simulation and confining pressure loading mode is given. Then, the 3 D finite element model of 15-ring fine segment structure is established, and the distribution patterns of stress and deformation of lining segments under normal service condition are analyzed. Afterwards, the linear buckling mode and nonlinear ultimate stability bearing performance of lining segments under extreme loading condition are studied. Finally, considering the ways of full-ring reinforcement and spacer-ring reinforcement, the reinforcement effect of high performance ferrocement(HPF) on the ultimate bearing performance of lining segments is discussed. The result shows that(1) under the external confining pressure, the lining segments present an horizontal overall deformation form similar to flat ellipse;(2) under normal service condition, the maximum Von Mises stress of the segment is 0.585 times of the uniaxial compressive strength, and the corresponding deformation ovality of the maximum full displacement is 4.03‰, which meets the specification requirements and has good bearing performance;(3) under extreme loading condition, the variation trend of loading-displacement curve is linear rapid increase, nonlinear gentle increase and tends to be gradually convergent, and the ultimate loading coefficient of the segments is 3.522, which has good nonlinear stable bearing performance;(4) HPF reinforcement can effectively improve the ultimate bearing capacity of segments, the ultimate bearing capacity of segments after spacer-ring reinforcement and all-ring reinforcement is increased by about 8.26% and 17.80% respectively compared with the segments without reinforcement.