Numerical simulation of circular tunnel intersections in anisotropic rock mass

Abstract

Jointed and fractured rock masses are often encountered during underground excavations. Their anisotropic behaviour is crucial for stability assessments of engineering structures; such as tunnel intersections. This paper investigates the effect of rock mass anisotropy on the intersection of circular tunnels using 3D Finite Difference Method (3D-FDM). The results of the study show that the discontinuities in the anisotropic rock mass differentiate the stress field around the tunnel section, as the values of the principle stresses are oriented according to the joints’ direction. Maximum displacement is developed in the areas where the discontinuities are tangential to the tunnel section, indicating the significant effect of the ani-sotropy’s orientation. In addition, the plastic zone becomes asymmetric around the tunnel intersection, with a greater expanse in the areas where the rock mass discontinuities are tangential to the excavation.