Flexural behavior of precast tunnel segments reinforced by macro-synthetic fibers

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. The design process of segmental concrete linings in ground conditions generally refers to standard load cases of demolding, storage, transportation, embedded ground condition, grouting process and TBM thrust jack phase. Excluding the latter loading condition, a flexural bearing capacity of segments is generally required both at provisional and final stages. Within this framework, the present study investigates the possibility of using macro-synthetic fibers in precast tunnel segments by means of an experimental program on full-scale segments, which are part of a tunnel lining with an internal diameter of 3.5 m. To this aim, a preliminary material characterization on standards small samples was carried out in order to select a PFRC adequate for use in precast tunnel segments. The PFRC selected was used for casting two full-scale segments to be tested under three point bending tests.