PSI - Issue 84

I. Vangelisti et al. / Procedia Structural Integrity 84 (2026) 1247–1254

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Table 1 – Reference parameters for the evaluation on the levels of knowledge. ID Applicability

Parameter

1 2 3 4 5 6 7 8 9

Entire tunnel Entire tunnel Entire tunnel Entire tunnel

As-built documentation

Tunnel excavation methods

Geometrical survey

Defects survey

Single inspection lining segment Single inspection lining segment Single inspection lining segment Single inspection lining segment Single inspection lining segment Single inspection lining segment Single inspection lining segment

Compression concrete strength

Flat jack tests

Georadar

Video endoscopic inspections

Previously rehabilitation interventions

10 11

Exceptional events

SHM data (if available)

To assess the level of knowledge of an inspected segment, it is necessary to identify, in accordance with Table 2, the level of knowledge for each of the 11 representative parameters, based on the data collected through the critical analysis with reference to the i-th segment. For parameters that do not vary from one segment to another, the corresponding level of knowledge is defined only once at the beginning of the procedure.

Table 2 – Definition of the levels of knowledge for each reference parameter and for each type of verification.

In order to assess the global level of knowledge of an inspection segment, a method based on the combination of all parameters is proposed. In particular, a weight w is assigned to each parameter, as reported in Table 3. The weight w is a fixed parameter for all tunnel lining inspection segments. Depending on the level of knowledge achieved for the i-th parameter, the corresponding coefficient can be identified. The global level of knowledge of the segment is obtained by summing all the individual products between the weight and the coefficient associated with the Knowledge Level. By using Table 4 it is possible to identify the final levels of knowledge of the individual inspected segment. The proposed intervals were calibrated on real case studies identified by the Working Group, for which the level of knowledge was known. It should be emphasised that the contribution of any monitoring data must be considered only when the monitoring system has actually been installed.