Abstract: On July 19,2024,a bridge on the Daning Expressway in Shazhou County,Shaanxi Province collapsed due to
sudden flash floods and a sharp rise in water levels,causing significant damage. To effectively detect and warn of such disasters,
the PS-InSAR technique was adopted,combined with high-resolution drone images and rainfall data,to conduct a systematic
analysis of the surface deformation in the collapsed area from June 2022 to July 2024. The study explored the temporal and
spatial evolution characteristics of the deformation and its potential correlation with the collapse event. The results showed that
the collapsed area exhibited significant abnormal deformation signals within 2 years before the collapse. The spatial and temporal
distribution of surface deformation in the collapsed area and its surrounding regions was uneven,and the deformation rate in
most areas was -5 mm/ a to 5 mm/ a. Through the time series analysis of typical deformation points,it was found that the deformation
had seasonal variation characteristics,with the uplift rate slowing down in summer and turning to subsidence in winter.
Five days before the collapse,the deformation volume suddenly increased to -10 mm to -20 mm,indicating that the surface
deformation had entered an abnormal fluctuation stage. Additionally,the abnormal deformation signals on August 6,2022,and
July 14,2024,were both synchronous with intense rainfall events,with the maximum rainfall reaching approximately 12 mm/ d.
The intense rainfall caused the groundwater level to rise rapidly,exacerbating the uneven subsidence of the strata,and subsequently
triggering abnormal surface deformation. The study results revealed the intrinsic relationship between rainfall changes
and surface deformation,providing a scientific basis for the early warning of sudden geological disasters on expressways,and having significant theoretical and practical significance for the safety guarantee of transportation infrastructure.