De Stefano, Rita (2023) Monitoring and stability of the banks of the large dams. [Tesi di dottorato]

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Abstract

Monitoring is an essential tool for ensuring safety of large civil engineering works during their construction and service life in terms of maintenance and prevention. Large dams are critical for safety since the catastrophic human and socio-economic consequences in case of failure. Displacement measurements characterize the static response of the dam embankment and its interaction with the soil mass and are traditionally performed by means of assestimeters and inclinometers (dam body displacements) and optical precision levelling and GNSS (surface displacements). The integration of ground-based measurements with remote sensing techniques can largely improve the efficiency of monitoring systems. Among the remote sensing techniques, the Synthetic Aperture Radar Differential Interferometry (DInSAR) has been proved its versatility and efficiency for mapping and monitoring deformations of the Earth's surface (Di Martire et al., 2016, Confuorto et al., 2017), subsidence and sinkhole phenomena (Tessitore et al., 2018), as well as infrastructures (Albano et al., 2016; Infante et al., 2018). DInSAR technique can implement wide range analysis that exploits the medium and high resolutions (20m × 4 m and 3m × 3m) and short revision time (6-8 days) of the Sentinel-1 and COSMO-SkyMed constellations. Due to the availability of a large historical set of data, measured displacements on targets can reliably improve and enlarge the dataset achievable with conventional methods. In the thesis the suitability of developing an integrated monitoring system, based on the complementary use of remote sensing and traditional techniques, has been verified with reference to the case study of a rockfill dam. Menta embankment Dam is located in Southern Italy and was built between 1987 and 2000 as the main reservoir of the new aqueduct system serving the city of Reggio Calabria. The dam was monitored from 2011 to 2022, during the experimental and operational reservoir period. Particular attention was paid to the experimental reservoir period (2011 to 2018) by performing a multi-band satellite analysis (X and C band) in ascending and descending geometry. The satellite data were compared with the inclinometric data in order to validate the technique and for a better understanding of the dam behaviour. In addition, inclinometric and satellite data were compared with the main acting cause, the reservoir level. The inclinometer data show displacements over time, consistent with the stress-strain picture of the structure of the maximum order of approximately 1.5cm, as do the satellite data. furthermore, the displacements obtained from the satellite data are consistent with the dam's reservoir and reservoir levels.

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