Structural behaviour of precast tunnel segments in fiber reinforced concrete

An experimental research on the possibility of using fiber reinforced concrete precast tunnel segments instead of traditional reinforced concrete (RC) elements is presented herein. This solution allows removing the traditional reinforcement with several advantages in terms of quality and cost reduction.The case of precast elements used with a Tunnel Boring Machine (TBM) in the Brennero Base Tunnel has been considered.Full-scale tests on both traditional reinforced concrete and fiber reinforced elements have been performed. In particular, bending tests were carried out in order to compare the behaviour of the segments under flexural actions, while point load tests were developed with the aim of simulating the thrust force induced by the Tunnel Boring Machine, and then the effect of load concentration and splitting phenomena.The tests results showed that, in this peculiar application, the fiber reinforced concrete can substitute the traditional reinforcement; in particular the segment performance is improved by the fiber presence, mainly in terms of cracking opening control.