Fiber reinforced concrete combined with traditional reinforcement for use in precast tunnel segments

The paper focuses on the advances in precast tunnel segments with particular reference to the reinforcement for use in these elements. The behavior of segmental tunnel lining of Brescia Metro is investigated at the final state, thus under the embedded soil load condition. A parametric study was carried out to assess the influence of the stiffness of longitudinal and ring joints on the internal forces acting on the lining. Furthermore, different tunnel depths were considered in order to get a better understanding of the sectional response of the tunnel lining. The study was developed by means of numerical analyses based on a 2 ½ dimensional model. Finally, after the evaluation of the forces applied on the lining, the interest was focused on the optimization of the reinforcement (fiber and rebars) with respect to the embedded-soil load-condition. Therefore, the tunnel lining behavior at ULS was considered.