Deformation Monitoring and Analysis of Railway Bridges Integrating Time-Series InSAR and Finite-Element Modeling

Interferometric Synthetic Aperture Radar (InSAR) is widely employed for measuring millimetre-level deformation of bridges and other structures. However, retrieving multi-dimensional displacements of a bridge and integrating these measurements with structural stress for coupled analysis remains a major challenge. To address this issue, we propose an integrated framework and demonstrate its application to the Hutiaohe extra-large bridge in Guizhou Province. First, a two-dimensional E-PS-InSAR time-series method is developed to derive the bi-directional deformation of the bridge. Next, structural temperatures are obtained via the ANUSPLIN interpolation scheme, enabling accurate isolation of the thermal response. Finally, the finite-element model (FEM) of the bridge is established to interpret the observed deformation and thermal signatures within the structural context. The results indicate that, compared to conven-tional InSAR approaches, the proposed framework provides a richer set of insights of multi-dimensional deformation, structural behavior, and thermal effects.