Work

Transverse seismic performance and fragility analysis of shield tunnels considering different internal structural configurations

Year: 2026

Type: article

Abstract: The influence of internal structures on the seismic behavior and damage mechanisms of large-diameter shield tunnels remains insufficiently quantified in existing fragility studies. This study develops a refined three-dimensional numerical framework incorporating soil–structure interaction (SSI) and conducts Incremental Dynamic Analysis (IDA) to evaluate the seismic vulnerability of shield tunnels with different internal structural configurations, including non-deck, single-deck with low and high inter-story heights, and double-deck tunnels. The numerical results show that internal structures increase the transverse stiffness of the tunnel system, thereby reducing global ovaling deformation and suppressing joint openings in cast-in-place regions. However, the resulting stiffness discontinuities and deformation redistribution intensify tensile damage at the connections between the internal structures and the segmental lining. Fragility analyses further indicate that drift-related functional damage of the internal structures can become critical even when the global deformation of the segmental lining remains comparatively limited. Peak Ground Acceleration (PGA) is identified as the preferred intensity measure for the lining-related diameter change ratio, whereas Acceleration Spectrum Intensity (ASI) performs best for the drift-related response of the internal structures. These results demonstrate that evaluating the segmental lining alone may overestimate the seismic capacity of the tunnel system. The proposed framework provides a basis for system-level seismic performance assessment of large-diameter shield tunnels with internal structures.

Source: Soil Dynamics and Earthquake Engineering

DOI: 10.1016/j.soildyn.2026.110728