PSI - Issue 84

I. Vangelisti et al. / Procedia Structural Integrity 84 (2026) 1239–1246

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6. Conclusions This paper presented a methodological proposal for the execution of the Level 3 Preliminary Assessment , in compliance with the Tunnels Guidelines. The proposed approach is document-based, relying on a detailed analysis of the available documentation aimed at reassessing the tunnel attention class. The scope of application of the proposed procedure is limited to the Global Structural and Geotechnical (GSG) and Local Structural (LS) attention classes. For lining inspection segments for which a reduction in the attention class with respect to the original classification is hypothesised, lining stress measurements are required in order to verify if it is loaded or not loaded . If it results as unloaded, that is the medium stress value obtained from concrete stress tests is lower than 0.5 Mpa, the reduction in the attention class is then validated; otherwise, with reference to σ , that is the stress value recorded on the tunnel sidewalls for which the capacity/demand ratio is higher than 1.5 in the most loaded section, the execution of a simplified lining verification (if the stress is comprises between 0.5 and σ ) or of a VAL4 (if the stress is higher than σ ) is required. Finally, a procedure for the prioritization of lining inspection segments requiring VAL4 has been presented. This procedure consists of a first level of prioritization at the lining-segment scale, followed by a second level of prioritization at the overall tunnel scale. Acknowledgements This study was supported by FABRE – “Research consortium for the evaluation and monitoring of bridges, viaducts and other structures” (www.consorziofabre.it/en) through the project “ARCITunLin – Assessment, Risk Classification and Interventions on TUNnel LINings”. Any opinion expressed in the paper does not necessarily reflect the view of the funder. References

Italian Ministerial Decree 247/2022, "Guidelines for risk classification, safety assessment, and monitoring of existing tunnels". Italian Ministerial Decree 17/01/2018, Italian Technical code for the design of civil and industrial buildings.

Circolare n°7-2019 C.S.LL.PP for the application of the Italian Ministerial Decree 17/01/2018 Highways tunnel inspection manual 2020, Italian Ministry of Infrastructure and Transport

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