Application of the italian Guideline during landslide risk inspection for bridges: definition of a checklist and its application to some case-study

The large number of major infrastructures in the Italian territory, such as bridges and viaducts, is in a clear and increasing state of neglect and was designed according to outdated standards. Among the problems are the management of viaducts by different entities, inadequate maintenance, and the reaching of the end of the useful life of the structures. Striking collapse cases, such as that of the Morandi bridge, have also brought the issue to the public's attention. Italy is also one of the most at-risk countries in Europe for landslides and floods: according to the latest “Rapporto sul Dissesto Idrogeologico in Italia”, published by ISPRA every year, over 18% of the national territory is mapped in the highest hazard classes, including, consequently, many bridges and viaducts. Since the safety risks associated with such important structures must be absolutely kept within acceptable limits, Italian institutions approved in 2020 the “Linee guida per la classificazione e gestione del rischio, la valutazione della sicurezza ed il monitoraggio dei ponti esistenti”, specifically focused to classify and manage associated risks, defining the priority order for interventions and bridges monitoring. These guidelines are considered an advanced tool, capable of standardizing assessment and, consequently, assisting infrastructure managers on a national level. This thesis work aims to analyse these Guidelines in detail, starting from the definition of risk and the classification of the landslide typology and covering all the steps of its multi-level approach. The Guidelines will then be specifically applied to 4 case studies and compared with the results obtained with the application of other alternative algorithms, in particular one proposed by Tecne, that also aim to create a priority ranking for bridge interventions. Chapter 4 will deepen the topic of the inspection phase, which is, together with the census, at the base of the risk assessment system, with the aim of defining a defect checklist that could help to recognize a landslide risk for the viaduct. The final chapter will delve into an important topic for bridges that received a higher risk class after the application of the Guideline: the estimation of the foundation length, with the aim of presenting the main existing techniques for its determination and their range of applicability.