MODELLING PROGRESSIVE HARDENING OF SHOTCRETE IN CONVERGENCE-CONFINEMENT APPROACH TO TUNNEL DESIGN

The progressive hardening of shotcrete used for tunnel supports is of great importance because it influences the support response to ground movements and therefore the stresses induced in the shotcrete lining. A new model, which can take into consideration of the hardening of concrete and provides the convergence-confinement curve of the supported tunnel, is presented. The model is used to back-analyse the measurements taken in the Kielder Experimental tunnel and presented in technical literature. An axisymmetrial numerical model (FLAC code) has been also set up for comparison with the proposed model results. Both the in situ measurements and the numerical results using FLAC are in good agreement with those computed using the proposed convergence-confinement method.