Slope stability radar
The Slope Stability Radar (SSR) is a new application for the monitoring of slope stability at open-cut mines. It is a system currently in use across the global mining and civil industries.
Slope stability is a critical safety and production issue for open-cut mines around the world to understand the probability of mine wall failures. Many fatalities have occurred in mining due to slope failure - sudden rock and wall collapses. Even when there is no injury, there is a high cost due to lost production and often damaged equipment. A common technique to determine slope stability is to monitor the small precursory movements, which occur prior to collapse.
Slope Stability Radar, as a contemporary slope stability analysis tool, have been developed to remotely scan a rock slope to monitor the spatial deformation of the face. Small movements of a rough wall can be detected with sub-millimeter accuracy by using interferometry techniques. The effects of atmospheric variations and spurious signals can be reduced via signal processing means. The advantage of the slope stability radar over other monitoring techniques is that it provides full area coverage without the need for mounted reflectors or equipment on the wall. In addition, the radar waves adequately penetrate through rain, dust and smoke to give reliable measurements, in real-time and twenty-four hours a day.
A series of time measurements over time can be used to track movement of the rack slopes, and also detect variations in the rate of movement, which indicate instability. The radar information can be combined with various other information on a graphical display. Typical examples are 3-D models of the rock surface or pictures of the slope being monitored.
Slope stability radars are currently manufactured by companies in Australia, South Africa and Italy.
Terrestrial SAR Interferometry (TInSAR)
Terrestrial Interferometric Synthetic Aperture Radar (TInSAR) is a remote sensing technique for the monitoring of displaqcements and deformations. TInSAR technique is based on the same operational principles of the Satellite SAR Interferometry: the displacement along the instrumental Line of Sight (LOS), is computed as the phase difference between two SAR images (interferometric technique). TInSAR final outputs are 2D images where the displacement of each pixel can be identified by false colours. Furthermore, displacement time histories of each pixel can be derived by multi-stack analyses. The displacement accuracy ranges from few tenths of millimetre to few millimetres, depending on the operational distance and on the atmospheric conditions. Finally, thanks to the high sampling rate (few minutes) TInSAR can be used also for the real-time monitoring finalized to early-warning. TInSAR is a suitable technique for the detailed and continuous monitoring of slope instabilities since it allows the pervasive sensing of the whole slope; in this way, infromation about the dynamics of the instabilities can be achieved. Among the most common fields of applications are rock scarps, volcanic flanks, localized subsidences, glaciers etc.
External links
- Terrestrial SAR Interferometry (TInSAR)
- Landslides monitoring by TInSAR technique
- Rock falls monitoring by TInSAR technique
- Monitoring of geological instabilities by TInSAR technique
References
- Mazzanti P., 2011. Displacement Monitoring by Terrestrial SAR Interferometry for Geotechnical Purposes. Geotechnical instrumentation news (Giugno 2011), pp. 25-28.
- Mazzanti P., Bretschneider A., Brunetti A., 2011. Geomechanical investigation of coastal cliffs by remote sensing techniques. Proceedings of the 8th International Symposyum on Field Measurements in Geomechanics (Berlino, 12-16 Settembre 2011) (Poster)
- Bozzano F., Cipriani I., Mazzanti P. & Prestininzi A, 2011. Displacement patterns of a landslide affected by human activities: insights from ground-based InSAR monitoring. Natural Hazards, DOI: 10.007/s11069-011-9840-6.
- Mazzanti P., Brunetti A., 2010. Assessing rockfall susceptibility by Terrestrial SAR Interferometry. In: Malet J.P., Glade T., Casagli N. (eds), Proceedings of the Mountain Risks International Conference, Firenze, Italy, 24-26 November 2010, pp. 109-114.
- Bozzano F., Mazzanti P., Prestininzi A., 2008. A radar platform for continuous monitoring of a landslide interacting with an under-construction infrastructure. Italian Journal of Engineering Geology and Environment, 2, 35-50.
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