Nuovi strumenti per il progetto ed il monitoraggio di elementi critici della sovrastruttura ferroviaria

This work was developed as part of mission 4: education and research in the field of sustainable mobility under the National Recovery and Resilience Plan. It takes an integrated approach to characterizing materials, monitoring and modelling the railway superstructure. The aim is to develop physical and digital experimental tools to support the design and maintenance of railways. The first contribution outlines a procedure for the mechanical and functional characterization of bituminous materials used in sub-ballast layers. These layers are crucial for the performance and durability of the entire superstructure and railway track. A laboratory procedure has been developed to simulate the interaction between the stone elements of the ballast and the underlying bituminous layer; this procedure is called a punching test. To this end, an Adaptive Indentation Plate (AIP) support was designed with five truncated pyramidal tips to replicate the contact points of the ballast on cylindrical specimens (Φ150 mm). An experimental study was conducted to validate the proposed test and identify its characteristic parameters, revealing significant differences between the tested mixtures. In the field of railway monitoring studies, the focus is on developing and testing wayside monitoring systems to assess the behavior of the superstructure during the passage of rolling stock. To this end, a multimodal framework was developed to enable synchronized acquisition of optical and accelerometric data. This framework was then tested in the field at San Giacomo di Guastalla (RE). The results confirmed the effectiveness of the framework, identifying significant correlations between displacements and accelerations, as well as behavioral differences related to train type, direction of travel, and local superstructure conditions. Structuring the coordinated installation as parameterized tuple sets and linking them to measurable performance indices enables the framework to be reproduced and compared across sites. The research was then extended to include the development of digital twins of the superstructure, incorporating field measurements. As a central case study, bonded insulated joints, a critical point of the track, were analyzed and modelled to investigate their behavior and performance under operational conditions. The digital twin was then used to simulate potential degradation scenarios by varying parameters such as the gap value (ΔL), bolt preload, bonding conditions and support properties. To optimally implement the digital twin, refine the multimodal monitoring approach and gain in-depth analysis of the interactions between infrastructure layers, a dedicated laboratory testing setup has been designed. This comprises a newly conceived test frame designed to host a full-scale track section. This multifunctional prototype, named Railway Superstructure Test Frame (RSTF), replicates the boundary conditions and loading representative of real railway substructure behavior in a laboratory environment. It simulates the effect of a trains' load on all the track's layers and continuously monitors the structural response under controlled and repeatable conditions. Building the prototype provided a flexible experimental environment in which to recreate, test and analyze a full railway section, incorporating the entire superstructure and the bituminous sub-ballast layer. The results obtained open up possibilities for the practical application of research in the railway sector based on targeted laboratory tests, large-scale wayside monitoring campaigns, and advanced numerical modelling. The aim is to promote the operational adoption of these results to improve the overall performance, safety and sustainability of the railway network.