Innovative FRC Design for Underground Applications (inner lining, shaft, CIP) using a New Generation of Fibres
The behaviour of fibre reinforced concrete is more than a simple superposition of the characteristics of the concrete matrix and the fibres; to analyze the behaviour of this composite material, also the interaction between both has to be taken into account, i.e. the transfer of loads from the concrete matrix to the fibre system. A unique concept of fibres have been developed which combined high tensile strength + perfect anchorage (double hook) + ductile wire. Consequently we get a very high pull out force and steel is elongating. The intrinsic mechanical properties (Young’s modulus, anchorage and tensile strength) of the fibre allows the forces to be absorbed without breaking or excessively elongating the fibre. This unique post cracking behaviour has been used to design very innovative solutions. Three projects will presented in this paper: the inner lining of Lee Tunnel (UK) submit to internal pressure, the Jansen Mine shaft in Canada where shaft walls are slip formed and a CIP tunnel in Turkey. All design approaches have been supported by a specific testing program conducted by independent parties to validate the material property. The result will also be summarized in this paper.