Postconstruction Deformation Characteristics of High-Fill Foundations of Kunming Changshui International Airport Using Time-Series InSAR Technology

The Kunming Changshui International Airport was built on complex mountainous terrain with significant fluctuations in Southwest China. The site contains large areas of high fill susceptible to uneven ground deformation from filling material consolidation, dynamic loading from aircraft, and other factors. Thus, monitoring and analyzing the causes and characteristics of postconstruction deformation of high-fill foundations are crucial to the airport's safe operation. In this study, we obtained a total of 149 Sentinel-1A ascending SAR images from March 2017 to March 2022. We estimated the elevation error and corrected the topographic phase to mitigate the impact of large topographic fluctuations on monitoring. Then, we extracted ground subsidence results based on time-series InSAR technology. The results show that deformation mainly occurred in the high-fill areas during the monitoring period, whereas settlement was more pronounced when the fill height was over 30 m. The deformation rate is influenced by the height of the fill, ground reinforcement measures, and dynamic loading of aircraft. Using the Mann-Kendall trend analysis and Pettitt mutation test methods to detect temporal information from time-series points, we found that the time required for the foundation to reach a stable state after construction is not directly related to its residual subsidence. Other factors, such as construction measures also influence it.