Advanced Data Processing of Ground-Based Synthetic Aperture Radar for Slope Monitoring in Open Pit Mines

Nowadays ground-based Synthetic Aperture Radar Interferometry (GBInSAR) is used internationally as a leading edge tool for the near real time monitoring of slope movements on landslides and open pit mines for either safety-critical and background monitoring purposes. The success of the technology relies mainly on its ability to rapidly measure slope movements with sub-millimetric accuracy over wide areas and in almost any weather conditions. In recent years, GBInSAR has experienced significant improvements in its performances, thanks to the development of more advanced radar techniques on both data processing and sensor performances. In this paper an advanced data processing chain able to simultaneously measure a wide range of deformation rates, across four orders of magnitudes, from very fast movements (up to 150 mm/hour) to extremely low displacements (few mm/month), is presented. The new processing may result in an early detection of slow movements making possible to support mine planning activities, to review extraction methods, mine design, ground support and monitoring practices before movements start to interfere with operations and any problem become difficult or too expensive to be managed. The processing method is presented along with recent successful studies in several Brazilian iron ore mines with different characteristics, owned by Vale S.A. In the sites radar data have been integrated and compared to displacement measurements acquired by radar images and total stations over tens of prisms, in order to improve the interpretation of the local slope movements. This technique could be applied to support long term monitoring in extensive areas adding to the traditional systems and also to define target areas for deeper investigations.