Fiber reinforced concrete for tunnel linings

The paper concerns the design of Steel Fibre Reinforced Concrete (SFRC) precast tunnel elements, based on the new international building code, the fib New Model Code. Precast elements for tunnel linings are designed by considering several loading conditions. Some of these loading configurations can be studied by means of simplified analytical approaches which enable to easily include the FRC resistant contribution according to fib Model Code. On the other hand, some mechanisms need to be studied by means of nonlinear analyses based on fracture mechanics in order to properly assess the benefits due to fibres. These mechanisms generally occur during the lining construction process, since they are correlated to the introduction of the TBM’s thrust jack forces (thrust jack phase) or depend on torsion effects caused by the ovalisation of lining rings outside the TBM’s shield during the grouting process. The present paper concerns the study of a segmental tunnel lining by means of non-linear numerical analyses concerning the so-called thrust jack phase. The FE analyses are carried out by using the constitutive fracture-law proposed by the fib New Model Code