Settlement is the key point for safety monitoring of super-large pile group foundation built on thick bed overburden. According to the question existing in the settlement monitoring of pile group foundation in Sutong bridge

PSI (permanent scatterers interferometry) and CRI (corner reflectors interferometry) technologies are synthetically applied to the settlement monitoring for Sutong bridge foundation. Combining with the permanent scatterers characteristics of the bridge and corner reflectors set up in the key monitoring site at bridge region

by processing 20 scenes SLC (signal look complex) data of Envisat acquired in the construction period from 2003 to 2008

differential interferometry is analyzed by CTM module in EV-InSAR software. The permanent scatterers points in the bridge area are picked out and the deformations of the points in different construction periods are calculated by PSI and CRI joint algorithm. It reflects the settlement of Sutong bridge foundation in the construction process objectively and roundly. Comparing settlement values gained by PSI with finite element calculation

the relative error is 4.64%. The result indicates that PSI and CRI joint algorithm is a powerful technology to monitor the foundation settlement of huge bridge's foundation. Along with continuous accumulation of SAR (synthetic aperture radar) data in the monitoring area

high-precision settlements of Sutong bridge foundation in operation period will be gradually obtained.