Comparison of New-Generation Carbon Fiber Linings and Traditional Concrete Tunnel Segments in European Metro Infrastructure

The rapid expansion of European metro networks and the urgent need to reduce embodied carbon in underground infrastructure have intensified interest in alternative lining materials that can outperform traditional concrete tunnel segments. This study examines the structural behavior and sustainability implications of new-generation carbon-fiber lining systems in comparison with conventional ultra-high-performance fiber-reinforced concrete (UHPFRC) segments. A comprehensive experimental program was carried out to characterize the mechanical response of UHPFRC mixtures incorporating various steel fibre lengths (۸, ۱۲, and ۱۶ mm) and dosages (۱-۶%). Results demonstrated that increasing fibre content enhanced compressive strength, splitting tensile capacity, crack resistance, and flexural behavior, with short fibres providing superior strain-hardening performance and long fibres improving post-peak ductility. These benchmark results were then used to contextualize the performance advantages of carbon-fiber linings, which offer significantly higher tensile capacity, reduced section thickness, corrosion-free durability, and substantial reductions in embodied carbon. The comparison highlights the potential for carbon-fiber linings to replace or supplement traditional concrete coatings in future European metro tunnels, enabling longer service life, reduced maintenance, and alignment with sustainability objectives.

کلیدواژه ها:

Carbon-fiber tunnel linings ، UHPFRC ، Metro tunnels ، Structural performance