Investigation into the Application of PP Fibres in Primary Lining

The results of laboratory research and field tests to investigate the possibility of using the polypropylene (PP) fibres instead of steel wire meshes in concrete for tunnel lining are presented. The laboratory research included testing the properties of different sorts and shapes of PP fibres and one type of St fibres, bond properties (pull-out tests) of PP fibres from different concrete mixes, standard bending test of concrete prisms and bending test of circular plates. With obtained parameters the analyses of stresses and strains in supporting structure by means of FLAC computer program were conducted, for different stages of construction, which included the interaction of primary layer with reinforced rock. For the sake of comparison test fields on the site were erected with PP fibres and steel reinforcing meshes.