Numerical study on the effects of TBM high-concentrated loads applied to precast tunnel segments

In the last two decades, Fiber Reinforced Concrete (FRC) was progressively adopted in several segmental tunnel linings. The benefits related to the inclusion of fiber reinforcement in the cementitious composites are several but, the most important, is the noticeable increase of the post-cracking tensile residual properties. Moreover, the fiber reinforcement enables a considerable boost of the tunnel elements production process. The application of the Tunnel Boring Machine (TBM) thrust jack forces is a critical temporary loading condition during the lining construction, since high-concentrated forces are introduced in the last installed precast segment. Fibers enable a stable development of splitting cracks and a possible reduction of stirrups placed in the regions under the thrust jacks. Within this framework, this paper aims at investigating the behavior of FRC precast tunnel segments during TBM operations by means of non-linear numerical analyses.