Constitutive modelling of fibre reinforced concrete and shotcrete

Fibre reinforced concrete and shotcrete have often been used in tunnel linings and in other applications such as industrial floors and pavements. The mixing of fibres into concrete or shotcrete can cause the material to resist the opening of cracks during failure. The design of these materials is not the same as for normally reinforced concrete, and there is not much in the way of rational design methods currently available. In relation to tunnel lining design, the phenomenon of rock mass squeeze out, or the use of rock bolts to anchor the rock base can lead to point loads on a fibre reinforced shotcrete lining. Therefore, this thesis investigates and develops the use of beam and panel tests which can be related a point load capacity to tunnel lining behaviour. The round determinate supported panel developed by Bernard (1999), is used in this manner for the evaluation of post-cracking behaviour in fibre reinforced concrete and shotcrete. Constitutive modeling of the behaviour of these panel specimens was carried out to assist in the interpretation of test results in the context of tunnel lining design. Yield line theory was then used to analyse the post-cracking behaviour of the fibre reinforced concrete and shotcrete panels to evaluate failure criteria. The cracks in round panels are always located at different positions in each panel test randomly. A probabilistic distribution function of crack position has therefore been determined using standard goodness of fit tests. The distribution function was then modelled using a Monte Carlo method to assess the effect of crack position on post-crack behaviour using yield line analysis. Experimental and numerical analyses have also been carried out to extend the experimental data and to assess the effect of thickness on the post-cracking behaviour of fibre reinforced shotcrete beams and panels. The test data from centrally loaded beam and round determinate supported panel tests was used to calibrate the numerical models. The principal outcomes of the research were successful modelling of post-crack behaviour of fibre reinforced concrete and shotcrete using yield line theory and prediction of cracking loads.