Investigation on the force transmission performance between segmental rings of super-large cross-section shield tunnels

With the development of shield tunnels towards larger cross-sections and more complex joint structures, the longitudinal–transverse coupling effect of segment structures has become increasingly significant. Assessing the force transmission effect between segmental rings is crucial for optimizing segment structures design. A full-scale loading test was conducted on staggered joint assembly segment structures to investigate the deformation of the segments, deformation of the joints, mechanical behavior of the reinforcement and bolts, force transmission behavior between segmental rings, as well as the failure progression and patterns of the segment structures. Based on this, a detailed 3D numerical calculation model, calibrated through full-scale tests, was utilized to analyze the effects of longitudinal pressure on the deformation of segment structures and the moment transfer coefficient between segmental rings. The findings indicate that the upper half-ring segment exhibited greater deformation compared to the lower half-ring segment, while both were larger than that of the middle ring segment. The longitudinal joint opening and circumferential joint dislocation in the upper half-ring segment underwent five distinct phases, whereas the lower half-ring segment experienced only three stages of variation. The difference in the mechanical behavior of longitudinal bolts resulted in greater shear stiffness for the circumferential joint under ordinal shear conditions compared to reverse shear. The evolution of the moment transfer coefficient occurred in four distinct phases. The contact between mortise and tenon markedly increased this coefficient, while plastic hinge formation in the segment structures led to a sharp decline. Additionally, the maximum moment transfer coefficient showed a positive relationship with longitudinal pressure, ranging from 0.4 to 0.7 when the pressure was between 0 and 3.0 MPa.