Subway Line Settlement Monitoring and Analysis Based on PS-InSAR Technology and Wavelet Packet Decomposition

Abstract. Ground subsidence induced by metro construction and operation can lead to structural deformation, posing significant threats to the safety of urban infrastructure. The Persistent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) technique enables high-precision monitoring of ground subsidence by extracting the interferometric phase of persistent scatterer (PS) points, demonstrating remarkable advantages in metro subsidence monitoring. However, due to the superimposed influence of multiple factors on the displacement signals of PS points, structural deformation signals are often obscured. Currently, there is a lack of effective methods for identifying structural deformation signals along metro lines. To address this, this study proposes a PS point analysis method based on Wavelet Packet Decomposition (WPD), which decomposes the time series of PS points into structural and non-structural deformation components, focusing on structural deformation induced by metro construction and operation. Using 32 Radarsat-2 images acquired from April 2019 to February 2023, ground deformation along Beijing Metro Line 16 was monitored and analyzed. The results demonstrate that the proposed method effectively captures structural deformation signals, revealing deformation characteristics associated with metro construction and operation. The study finds that structural deformation predominantly occurs during the construction phase, with ground subsidence showing a deceleration trend as operational time increases.