Attribution Analysis on Land Subsidence Feature in Hexi Area of Nanjing by InSAR and Geological Data

Hexi area is a key development region of Nanjing, which has suffered serious geological disaster of subsidence in recent years. To ensure the sustainable development, persistent scatterer interferometric synthetic aperture radar (PS-InSAR) was used to monitor the uneven land subsidence and the attribution was analyzed. Firstly, based on PALSAR and COSMO-SkyMed images, we used PS-InSAR technique to obtain the land subsidence in Hexi area from 2007 to 2016. The results were consistent with the leveling data in the same period, and root mean square error (RMSE) did not exceed 2.6 mm/a. Secondly, geological conditions, stratified subsidence and groundwater leveling data were combined to analyze the attribution of land subsidence feature. The results show that consolidation and compression of shallow strata is the main cause of uneven subsidence in Hexi area. The Entropy method was used to comprehensively evaluate the influence of uneven ground subsidence on the subway structure. The results show that the subsidence may affect the stability of subway structure when the main settlement soil layer is located below the tunnel.