Nowadays there is an increasing need to quantify the current and future performance of civil structures and infrastructures within a reliability-based framework, so that risks can be explicitly quantified for guiding effective mitigation measures.

Continuous monitoring of strategic infrastructures, such as dams and bridges, is a challenging task to control wide areas of the Earth surface or the built environment, with priority on those structures whose behaviour can result into severe economic and human losses. In the past, to monitor structural performance only on-site monitoring was carried out by placing several instruments close or inside the structure to measure physical quantities that could act as collapse precursors.

In recent years, remote sensing and satellite data analysis have proven to be very efficient in monitoring the actual state and behavioural evolution of strategic structures to quickly identify risk situations and generate appropriate alerts. The imaging capability of the current generation of SAR constellations has been significantly improved, and SAR images are now provided with meter to sub-meter spatial resolution with hundreds of images per individual site.

The combined use of remote sensing imagery and on-site data could strengthen the quality of the overall monitoring process.

In this proposal, the candidate will be involved in a consolidated research vein aimed at detecting ground or structure displacements by synergic use of data from multiple sources (including open access Synthetic Aperture Radar (SAR) images from the Copernicus Sentinel-1 satellite mission). Differential SAR Interferometry (DInSAR) processing chains, implemented using free tools provided by the European Space Agency (ESA), will be applied to SAR high coherence images in order to assess ground modification and displacement/deformation of strategic structures, such as dams and bridges.

Dams are fundamental infrastructures for water storage, electricity supply and flood protection. However, the risk of their failure, with uncontrolled release of water and consequent catastrophic flooding downstream, requires special attention in their management and operation to detect anomalous behaviors and adopt prompt countermeasures.

Nowadays, a growing concern is related to existing dams because of their age. Actually, in Europe and USA many dams were built after the Second World War and most of them are still in operation. The concern also extends to the new dams due to their increasing height. The maximum height of the post-Millennial dams, for instance, widely exceeds 200 m (worth mentioning is the 305 m high Jinping Dam in Sichuan, China) with a huge increase in risk exposure for the downstream population.

Permanent monitoring of these dams and their reservoirs is of paramount importance to prevent the risk caused by the eventual collapse of the main structure as recently occurred to an earth tailing dams in Brazil (Figure 1).

Bridges are of paramount importance in modern society for transportation and connection. Most of the Italian reinforced concrete bridges were built in the Seventies and degradation or other deficiency could have affected their current behaviour and could affect their future response under both ordinary and seismic loading. The same methodology based on Synthetic Aperture Radar (SAR) observations, could be applied for the assessment of bridge deformations. We will apply this methodology to obtain a detailed survey of some important Italian bridges, included the Morandi bridge (Polcevera Viaduct) prior to its collapse on August 14th 2018 (Figure 2). A displacement map for the structure from space-based SAR measurements will be generated to back-figure the occurred collapse.

Even though satellite image techniques do not allow distinguishing between stress accumulation or material degradation processes, they could be fundamental in detecting important structural deficiencies and anomalous behaviours.

Figure 2. Collapse of Morandi Bridge in Genoa in August 2018 (Italy)

The project proposal intends to begin students to modern signal processing methods for Earth observation through freely available satellite data from optical multispectral and synthetic aperture radar sensors. Specific applications will be chosen and the main tools proposed. For Synthetic Aperture Radar (SAR) data processing through interferometry and differential interferometry will be considered.

The project may include visits on the target structures that are analyzed through satellite images to validate the results. Such results will be compared with on-site data measured through traditional in-situ instrumentation and other InSAR measures obtained in literature.

The student will be jointly supervised by Prof. Silvia Ullo (https://www.unisannio.it/user/622/contatti), who has been working on satellite data analysis for years, Prof. Stefania Sica (https://www.unisannio.it/user/631/contatti)with expertise in geotechnical engineering and especially earth dams, and Prof. Maria Rosaria Pecce (https://www.unisannio.it/user/398/contatti), expert in structures, bridges and in diagnosis of their response.

References

· S. L. Ullo et al., "Application of DInSAR Technique to High Coherence Sentinel-1 Images for Dam Monitoring and Result Validation Through In Situ Measurements," in IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, vol. 12, no. 3, pp. 875-890, March 2019.

· S. L. Ullo et al., “Landslide Geohazard Assessment With Convolutional Neural Networks Using Sentinel-2 Imagery Data”, IGARSS 2019, Yokohama, Japan.

· D. Di Martire, R. Iglesias, D. Monells, G. Centolanza, S. S., M. Ramondini, L. Pagano, J. Mallorqui, and D. Calcaterra, “Comparison between Differential SAR interferometry and ground measurements data in the displacement monitoring of the earth-dam of Conza della Campania (Italy),” Remote Sensing of Environment, pp. 58–69, 2014.

· S. Sica and L. Pagano, “Performance-based analysis of earth dams: Procedures and application to a sample case.” Soils and Foundations, no. 49, pp. 921–940, 2009

· L. Pagano, E. Fontanella, S. Sica, and A. Desideri, “Pore water pressure measurements in the interpretation of the hydraulic behaviour of two earth dams ,” Soils and Foundations, vol. 50, pp. 295–307, 2010.

· S. Sica, L. Pagano, and A. Modaressi, “Influence of past loading history on the seismic response of earth dams,” Computers and Geotechnics, vol. 35, pp. 61–85, 2008.

· P. Addabbo, M. Di Bisceglie, M. Focareta, C. Galdi, C. Maffei, and S. Ullo, “Combination of Landsat and EROS-B Satellite Images with GPS and LiDAR Data for Land Monitoring. A Case Study: the Sant’Arcangelo Trimonte Dump,” IGARSS 2015, pp. 882–885, 2015.

· P. Addabbo, M. Di Bisceglie, M. Focareta, C. Maffei, and S. Ullo, “Integration of satellite observations and ground-based measurements for landfill monitoring,” IEEE Metrology for Aerospace (MetroAeroSpace), pp. 411–415, 2015.

· Pecce, M., F.. Ceroni, and G.. Maddaloni, "In-plane deformability of RC floors: assessment of the main parameters and influence on dynamic behaviour", BULLETIN OF EARTHQUAKE ENGINEERING, vol. 17, pp. 297–311, 2019.

· De Angelis, A., and M. Pecce, "Out-of-plane structural identification of a masonry infill wall inside beam-column RC frames",ENGINEERING STRUCTURES, vol. 173, pp. 546–558, 2018.

· Blasi, G., M. Antonietta Aiello, G. Maddaloni, and M. Pecce, "Seismic response evaluation of medical gas and fire-protection pipelines’ Tee-Joints", ENGINEERING STRUCTURES, vol. 173, pp. 1039–1053, 2018.

· Godat, A., F. Ceroni, O. Chaallal, and M. Pecce, "Evaluation of FRP-to-concrete anchored joints designed for FRP shear-strengthened RC T-beams", COMPOSITE STRUCTURES, vol. 176, pp. 481–495, 2017.