Title: Structural behavior of precast tunnel segments with macro-synthetic fibers during TBM operations: a numerical study
Author(s): Trabucchi, I.; Conforti, A.; Tiberti, G.; Plizzari, G.A.; Winterberg, R.
Publication: Symposium Paper
Appears on pages(s): 225-234
Keywords: Fiber reinforced concrete; Macro-synthetic fibers, Numerical analyses; Splitting phenomena; Thrust jack.
The use of fiber reinforced concrete in tunnel linings, with or without conventional rebars,
has increased in the two last decades, especially in segmental linings. In the meanwhile, in the
scientific community there was a growing interest on macro-synthetic fibers for use in
underground structures. Within this framework, the present study investigates the possibility
of using macro-synthetic fiber reinforcement in precast tunnel segments by means of a
Firstly, an experimental program based on three point bending tests was carried out on
polypropylene fiber reinforced concretes (PFRCs) characterized by different fiber contents in
order to assess their post-cracking residual strength. Secondly, the corresponding stress vs.
crack opening laws, representative of the PFRCs investigated, were calculated through
inverse analysis procedure. Then, a segment of a typical tunnel lining having small diameter
was adopted as reference to optimize the reinforcement solution (macro-synthetic fibers and
conventional rebars, i.e. hybrid solution) and to study its structural behavior by numerical
analyses. Particular attention was devoted to the Tunnel Boring Machine (TBM) thrust jack
phase, in which the TBM moves forward by pushing the thrust jacks on the bearing pads of
the latest assembled ring, introducing high-concentrated forces in the lining.