Prediction of convergences in rock tunnels excavated by conventional methods

This paper presents the application of an empirical equation for modeling the evolution of convergences (both as a function of time and distance to the face) in rock tunnels. To that end, convergence data from several case histories are employed, including tunnels recently constructed in Spain and also convergence data available from the literature. Results show that the predictive capabilities of the model are good, so that the model adequately reproduces the evolution of convergences with respect to time and to distance to the face. Finally, the influence of several factors (including support stiffness, tunnel depth, lithology and RMR, among others) on the back-analyzed model parameters (and, in particular, on the relative importance of rheological convergences vs convergences produced by the advance of the tunnel face) is investigated and results are discussed.