Post-construction subsidence characteristics and evolution of soft rock-filled subgrade at Bazhong Airport

In this study, Persistent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) technology was employed to analyze the spatiotemporal characteristics of pavement subsidence deformation, with the accuracy of the results validated through levelling surveys. Building on this, the causes of pavement deformation were investigated by integrating analyses of the airport's engineering geological conditions, precipitation and flight volume. The results indicate that deformation in the movement area has increased annually, with the maximum average yearly subsidence reaching 56.3 mm. The most pronounced subsidence occurred at the runway center and the 07-end, both located on erosional gullies with filled subgrade. A clear correlation, with r values ranging from 0.54 to 0.79, was observed between the subsidence rate and monthly precipitation, suggesting that rainfall infiltration and the characteristics of the fill material are the primary contributors to pavement deformation. In contrast, no significant correlation was found between subsidence rates and flight volume, indicating that aircraft wheel loading is not a major factor driving ongoing subsidence. These findings provide a scientific basis for the long-term maintenance, monitoring and risk assessment of airports constructed on soft rock fills.