The present work is divided in an introduction, four substantive chapters and conclusions. The first substantive chapter represents concrete in general – its history, basic components, as well as mechanical and other physical characteristics. Fibre reinforced concrete is presented next, followed by a brief history of adding fibres to materials and a description of concrete depending on the type of fibres used. Shotcrete and its dry and wet process of application is described at the end of the chapter. Second chapter focuses on the measurements of ultimate uniaxial compressive strenght of young steel fibre reinforced shotcrete, based on the test method recomended by RILEM. Test program consisted of three mixtures with different fibre content. Tests were performed on specimens after a period of 1, 2, 4, 8 and 12 hours. Specimens aged 1, 2, 3, 7 and 28 days were only tested for the ultimate compression strength. The data obtained this way leads to the fourth substantive chapter. The main principles of the NATM method are presented in chapter three together with the Dekani tunnel, as an example of successful application of steel fibre reinforced shotcrete. The last chapter contains parametric study, carried out to see how different contents of steel fibres in the mixture influence on tunnel excavation speed (at a constant thickness of shotcrete lining). Study was based on data gathered during the construction of a new tunnel Ljubno tube on the highway section Peračica – Podtabor (Ljubljana – Jesenice). This tunnel was built according to the principles of the new Austrian tunneling method (NATM). Conclusions are presented at the end
