GFRP Reinforcement for Segmental Linings of Mechanized Tunnels

The use of Glass Fibre Reinforced Polymer (GFRP) reinforcements is gradually spreading to replace or to integrate the traditional steel rebar for tunnels excavated with shielded TBMs and lined with precast segmental lining. The complete replacement of the steel rebar with GFRP is particularly used for segments that should be demolished after their installation, for example for cross-passages or niches realization. GFRP reinforcement cages placed on segments’ edges can play an important role to limit the number of cracks and local breakages caused by impacts and unforeseen load conditions, mainly before and during the lining installation. The analyses’ results on a 3D model, which allowed to consider the contribution of such reinforcements both during the lining erection and the service, show that they can increase the lining strength. Moreover, GFRP perimetric cages can be coupled with steel fibre reinforcement (SFRC) to increase the overall flexural and local resistance of segments. Examples of dimensioning and results of laboratory tests carried out to show the GFRP reinforcement effectiveness are reported.