A ground based radar platform was designed and it has been operating since the end of 2007. The aim is to control an unstable rock-slope in which tunneling works will be realized, in order to guarantee the workers safety and to control the evolution of the slope during the construction phases until its final structure. The Ground Based Interferometric Synthetic Aperture Radar system (GB-InSAR) has been installed in front of the monitored slope at a distance ranging from 700 to 1000 m.
A digital camera and a weather station have been coupled with the radar system in order respectively to collect photos for the continuous control of the work activities and to know in detail the weather conditions. The meteorological data are a basic tool to correct radar data and to analyse the relationships between rainfalls and the monitored landslide displacements. Both the GB-InSAR system and the weather station collect data every 5 minutes.
The complete remote control and data upload/download are obtained through a satellite WEB connection which allows for a daily automatic transfer of the data from the monitoring location to the CERI operational centre in Rome, where the processing is performed and interpretation and consequently decisions are taken. The data collected until now show that the system is able to detect displacements with an accuracy ranging from few mm to less than one mm for areas with high values of coherence and SNR (Signal Noise Ratio) independently to weather and light conditions.
The output data are 2-D maps of displacement along the instrument line of sight (interferograms) and the complete time series of displacement of a large number of pixels. These data allow to bound some sectors of the slope with different behaviour in terms of total occurred displacement and velocity. The location of the so defined sectors and theirs interpretation gave some insights into the natural and man induced dynamics of the unstable slope and suggest some procedures to optimize the GB-InSAR technique for similar cases.
This work has been realized thanks to grants and instruments of CERI, Research Centre for Hydrogeological Risks of the University of Rome "Sapienza".