ABSTRACT
In this article we will develop and detail all the technical challenges that have been taken up on this major project and the technical solutions that have been engineered for the use of ultra-high strength steel fibres in these tunnel lining segments. The Grand Paris Express is made of four new subway lines in Paris, numbered 15, 16, 17, 18, connected with the existing network, extending the lines 11 and 14, totaling of 200 km, 90% of which are underground. Sixty-eight new stations are built to accommodate more than two million passengers per day. The whole project will cost around 36 billion euros and will be completed in 2030. At the highest activity level, twenty TBMs will contemporarily dig the Parisian underground. With the aim to highlight new technologies and seeking sources of embedded carbon reduction and an increase in durability, the Société du Grand Paris has adopted the usage of the Steel Fibre-Reinforced Concrete for the Tunnel Lining Segments. After many investigations and tests, to date, four lots of these extensions have allowed for the usage of steel fibres, combining a total length of tracks around 48 km. This proves that this technology, which has been used for a long time in many countries, is now also validated in France. To achieve the specified mechanical requirements of the lines 16-2, 16-3 and 18-1, the precast concrete segments are exclusively reinforced with the ultra-high tensile strength ArcelorMittal Fibre Type: 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 and Long Itchington Wood HS2 in UK, Ejpovice Railway tunnel in Czech Republic, Świnoujście Road Tunnel in Poland.
