Evaluation of segmental lining response during shield tunnel construction based on field measurements and 3D FEM simulation

Lining safety can be threatened more severely at the construction stage than at the service stage, because the loads at the construction stage are larger. This study presents an in-situ experiment for measuring the loads acting on the lining and the internal forces of the lining to investigate the lining response during both the construction and service stages. A three-dimensional (3D) finite element method (FEM) model that could simulate the main relevant components of the shield tunnel construction process was employed to gain further insight into the mechanisms of the lining response. The influences of the key segment position and assembly sequence on the lining behavior were examined through a comprehensive parametric analysis. The results showed that during the assembly stage, the insertion of a key segment resulted in the most significant increase in the axial force, followed by the assembly of an adjacent segment. The lining responses were significantly influenced by the key segment, particularly during the construction stage, whereas the assembly sequence had a limited effect on the lining responses. During the construction stage, the closer the key segment to the tunnel invert, the greater was the axial force and the smaller was the bending moment of the lining. During the construction stage, the closer the key segment to the tunnel invert, the smaller was the axial force of the tunnel lining and the greater was the bending moment. The circumferential compressive stress reached its maximum value at the joint interfaces. Finally, the jack thrust force was the greatest at the tunnel invert. The key segment should not be placed at this location.