Design methods for fibre reinforced concrete
Fibre reinforcement has matured as a technology and it is now often used for tunnel linings in some countries, both in precast concrete segments and sprayed concrete (SFRS). For example, the Crossrail project in London features steel fibres for the segments in the running tunnels and also the permanent sprayed concrete linings for the station tunnels. While various design guides test methods and specifications exist, there remains some confusion about how best to use fibres. Test methods include beams and plates, both square and round, characterising the material in terms of energy absorption or flexural strength. There has been a vociferous debate about the relative merits of macro-synthetic and steel fibres. This paper reviews the state of the art and recommendations are made in terms of a consistent combination of the design approach, test methods and specification. The paper covers both soft ground and rock tunnels.