Improvement and validation of a multi-scale numerical model for shield tunnel seismic analysis

In this study, our First-Generation Multi-Scale Model (F-GMSM) was enhanced through two critical modifications: (1) a connector element-based 3D ring joint for the focus area of the numerical model, and (2) a distributed-type soil spring system to characterize soil-structure interaction (SSI) effects. To validate the effectiveness and robustness of this Second-Generation Multi-Scale Model (S-GMSM), refined 3D fully dynamic analyses were conducted and served as the benchmark for comparison. This 3D modeling methodology was validated through a shaking table test. The main findings and conclusions of this research are as follows: the mechanical response of Timoshenko beam-based bolts demonstrates significant mesh sensitivity, which consequently influences the opening deformation of ring joints under seismic loading; Under high intensity seismic excitation, the lumped soil spring system causes over 35 % overestimation of maximum joint opening widths in the multi-scale numerical calculations. Compared with the 3D reference model, S-GMSM achieves a 90 % reduction in computational time while maintaining joint opening width discrepancies (${\Delta }_m$) below 15 %. When peak ground acceleration (PGA) ≥ 0.3 g, ring joint openings on the soft soil side of the stratum interface increase significantly due to bolt yielding, yet remain below the temporary opening tolerance.