HPFRC TUNNEL SEGMENTS TO MITIGATE THE RISK OF EXCEPTIONAL LOADS

The paper presents some new design aspects aimed at the construction of prefabricated lining segments for urban tunnels in soft ground, able to ensure adequate structural performance under exceptional loads, such as fire and explosion within the structure. The design methodology and the advantages resulting from the adoption of high performance fiber reinforced materials, like High Performance Fibers Reinforced Cementitious Composites (HPFRCC) and Steel Fibre Reinforced Concrete (SFRC) and Textiles (TRC) are described in detail, pointing out that this design choice helps to improve structural response not only with reference to exceptional conditions, but also in the construction phases and for serviceability, thus increasing durability and sustainability. The design and construction of prefabricated tunnel segments represent the final experience of an INTERREG project named ACCIDENT - Advanced Cementitious Composites in DEsign and coNstruction of safe Tunnel - developed at three different levels, the material, the meso-structural and the macro-structural levels, to put in evidence the reliable advantages and the validity limits of the proposed design approach.