Infrastructure designTunnels and Geotechnics
Design of the repair interventions for the tunnel roof and related static verifications
Consortium for Sicilian Highways
The service concerns the repair works of the tunnel roof of the Telegrafo Tunnel on the A/20 Messina-Palermo motorway in the Palermo direction, following the damage caused by a heavy vehicle fire that occurred approximately 400 meters from the entrance on the Messina side on the night of December 24, 2022. The flames, high temperatures, and fumes released from the fire affected the pillars and the tunnel roof in the vicinity of the incident location.
As part of the service, a detailed inspection of the tunnel was carried out in accordance with the provisions of the Ministry of Infrastructure and Transport (MIT) Tunnel Manual, along with concurrent supervision of the concrete investigations to assess the structural condition.
Subsequently, design interventions were identified to ensure the safety of the damaged portion of the tunnel roof caused by the fire. These interventions involve the repair of the deteriorated part of the roof and the introduction of specific passive anchors (bolts) to increase the load-bearing capacity of the weakened roof.
The designed intervention extends for a distance of 55 meters from the fire source and involves the repair of the degraded part of the concrete roof by removing the deteriorated concrete layer, using a steel mesh, and applying tixotropic mortar containing high-strength synthetic polyacrylonitrile fibers.
As an additional structural intervention for safety purposes, the strengthening of the roof is also planned by introducing 182 passive bolts, positioned in a staggered pattern with a 2.00-meter spacing and anchored in the existing rock mass for a length of 3 meters.