Tunnel precast segments: An SFRC alternative ?

Steel fibre reinforced concrete (SFRC) tunnel segments were tested as an alternative solution to the classical precast reinforced concrete (RC) segments Since this loading has been considered as critical for the lining reinforcement, the experimental frame was designed in order to represent the bi-directional bending and torsion due to the badly equilibrated thrust of the tunnel boring machine, which may lead to failures (sometimes observed on site). The tests and measurements are described. The global behaviour, cracking process and failure modes of both types of segments are presented and discussed. For the SFRC segments studied, in the test configuration, the failure load is about 2.3 times smaller than the reference ultimate load of RC segments, which confirms the lack of ductility of deep SFRC elements under flexural loading. Laying SFRC tunnel segments would thus require specific care in steering and thrust applying.