Monitoring of High-Speed Railway Ground Deformation Using Interferometric Synthetic Aperture Radar Image Analysis  
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inclinometers and piezometers), have been widely used to assess ground stability and structural performance. These methods provide essential data for evaluating structural integrity, detecting potential hazards, and implementing timely mitigation measures. Precise Leveling: This technique measures vertical displacements by determining height differences between fixed points and is particularly effective in monitoring subsidence and uplift in geotechnically unstable regions. For instance, geodetic leveling can determine height differences accurate to a few millimeters over tens of kilometers, making it valuable for detecting vertical land motion. Geodetic leveling has been utilized in subsidence-prone areas to track long-term vertical movements and assess their impacts on infrastructure [9]. GNSS Surveys: GNSS technology enables the accurate tracking of three-dimensional positional changes over time. By utilizing continuously operating reference stations (CORSs) and periodic geodetic surveys, GNSS has significantly improved the accuracy and efficiency of ground movement assessments. The integration of GNSS with CORSs allows for precise positioning, enhancing the reliability of deformation monitoring. Studies have demonstrated that GNSS-based monitoring can effectively detect both rapid and gradual ground deformation, supporting the early detection of potential geohazards [10; 11; 12; 13]. While these methods offer high accuracy for localized measurements, they are inherently limited by high operational costs, labor-intensive procedures, and sparse spatial coverage, making them impractical for the large-scale, long-term monitoring of extensive high-speed railway corridors [14]. As a result, there is growing interest in adopting remote sensing technologies that can provide comprehensive, cost-effective, and continuous ground deformation monitoring across broad areas. Among these, Persistent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) has emerged as a leading technique for detecting millimeter-level surface displacement with high temporal resolution, independent of weather conditions and daylight [15; 16; 17; 18; 19]. PS-InSAR utilizes time-series Synthetic Aperture Radar (SAR) satellite images to analyze phase differences between acquisitions, allowing for the precise detection of surface movements over long periods. This technology is particularly advantageous for monitoring critical infrastructure, such as high-speed railways, where continuous ground stability is essential for safe operations [18]. Recent studies have demonstrated the successful application of PS-InSAR for monitoring urban subsidence, landslide progression, and the structural health of large-scale facilities [19; 20; 21]. However, its application to high-speed railway networks, which require high levels of accuracy and reliability in detecting subtle ground movements, remains an area of ongoing research and technological development [22]. Given the complex geotechnical conditions of the Honam High-Speed Railway, combined with the critical need for preventive maintenance and disaster risk mitigation, the use of PS-InSAR represents a promising solution for enhancing infrastructure resilience. By capturing the spatial and temporal patterns of ground deformation, PS-InSAR allows railway operators to identify early warning signs of potential subsidence-related hazards, prioritize maintenance interventions, and reduce the risk of operational disruptions [1].