PSI - Issue 84

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

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Table 2 presents the proposed prioritization for Case A, while Table 3 shows the prioritization scheme suggested for Case B. In order to determine the prioritization at the overall tunnel level, a diffusion index is introduced as a function of the distribution of priority levels among the individual lining inspection segments. This index sumarizes the prioritization information of all lining inspection segments within a tunnel into a single numerical indicator. The following procedure is proposed for its calculation: • evaluation of the number of lining inspection segments within each priority level; • application of predefined weights (presented in Table 4) to these quantities. The proposed weights have been calibrated on real case-study tunnels, in collaboration with ASTM group; • calculation of the diffusion index as the sum of the products of the corresponding percentages and weights.

Table 2 – Prioritization for lining inspection segments with a confirmed High attention class. Attention class Rock mass quality Concrete quality index

Segment prioritization

HIGH HIGH HIGH HIGH HIGH HIGH HIGH HIGH HIGH

HIGH HIGH

HIGH

PRIORITY4 PRIORITY4 PRIORITY3 PRIORITY4 PRIORITY3 PRIORITY2 PRIORITY3 PRIORITY2 PRIORITY1

MEDIUM

HIGH

LOW

MEDIUM MEDIUM MEDIUM

HIGH

MEDIUM

LOW

LOW LOW LOW

HIGH

MEDIUM

LOW

Table 3 – Prioritization for lining inspection segments with a High or Medium-High attention class with a loaded lining. Attention class Rock mass quality Concrete quality index Segment prioritization HIGH HIGH HIGH PRIORITY3 HIGH HIGH MEDIUM PRIORITY3 HIGH HIGH LOW PRIORITY2 HIGH MEDIUM HIGH PRIORITY3 HIGH MEDIUM MEDIUM PRIORITY2 HIGH MEDIUM LOW PRIORITY1 HIGH LOW HIGH PRIORITY2 HIGH LOW MEDIUM PRIORITY1 HIGH LOW LOW PRIORITY1 MEDIUM-HIGH HIGH HIGH PRIORITY4 MEDIUM-HIGH HIGH MEDIUM PRIORITY3 MEDIUM-HIGH HIGH LOW PRIORITY2 MEDIUM-HIGH MEDIUM HIGH PRIORITY3 MEDIUM-HIGH MEDIUM MEDIUM PRIORITY2 MEDIUM-HIGH MEDIUM LOW PRIORITY2 MEDIUM-HIGH LOW HIGH PRIORITY2 MEDIUM-HIGH LOW MEDIUM PRIORITY1 MEDIUM-HIGH LOW LOW PRIORITY1

Table 4 – Evaluation criteria for the concrete quality index. Priority

Weight coefficient