3-D NUMERICAL INVESTIGATION FOR TUNNEL STABILITY IN JOINTED ROCK

This paper investigates the impact of various basic factors affecting the stability of tunnel in jointed rock. These factors are density and orientation of joints, tunnel depth and the number of excavation steps. The tunnel stability will be evaluated through investigating; the creation and evolution of the deformations, evolution of plastic regions and stresses in the concrete lining and the surrounding jointed rock. Three-dimensional numerical investigation has been carried out for Brenner-Basis tunnel in Austria by two elastoplastic numerical models. These models are; four-parameters Ottosen plasticity model and Mohr-Coulomb criterion for concrete lining and rock mass, respectively. Different cases were analyzed with different combinations of tunnel depth, joint orientation, joint density, and number of excavation steps. The numerical results displayed the significant importance to consider these factors affecting the stability of the tunnel in jointed rock mass.