ABSTRACT
The aim of the article is to detail all the challenges that have been taken up on the Swinoujście tunnel project and the technical solution that have been engineered for the use of ultra-high strength steel fibres in the tunnel lining segments. The design and construction of the two-way road tunnel beneath the Świna river, required high levels of flexibility and expertise to ensure the development and implementation of a workable solution for each section of the tunnel route. Looking at new technologies and an increase in durability, the designer has adopted the usage of the Steel Fibre-Reinforced Concrete to reinforce the concrete for the lining of the tunnel without any additional reinforcement. For that, several tests have been preliminarily carried out to check the flexural tensile strength and the fire resistance of the material. These tests have proved that the steel fibre-reinforced concrete, which has been used for a long time in many countries, is now also validated in Poland. To achieve the specified mechanical requirements, the precast concrete segments are exclusively reinforced with the ultra-high tensile strength ArcelorMittal Fibre HE++ 90/60. ArcelorMittal, which has been manufacturing and producing steel wire fibers for more than 30 years, has supported the customers with its experience and know-how already acquired on other major projects abroad like: Doha Metro in Qatar, CrossRail, Thames Tideway Tunnel, Chiltern Tunnels in UK, Ejpovice Railway tunnel in Czech Republic. 1325 tonnes of ArcelorMittal HE++ 90/60 steel fibres were used in the reinforcement of the 500mm thick tunnel lining segments that were manufactured to line the tunnel. With an internal diameter of 12 meters, the Świnoujście two-way road tunnel is the largest internal diameter tunnel in Europe to date that is reinforced with steel fibres only.
