An Analytical Solution for Deformation of Underground Openings Excavated in Fractured Rocks

ABSTRACT: Excessive deformation of rock mass around underground openings are frequently encountered in mines and underground structures. It is particularly common in the tunnels excavated in soft rocks, the rock masses subjected to high in-situ stresses, and the weak rock masses that have been heavily sheared. Conventional approaches in the estimation of deformation in tunnels, such as Sulem et al. (1987), assumed that the tunnel is deep enough to consider that the stress distribution is homogeneous. However, in most cases in practice, the stress distribution around the tunnels are not homogeneous and isotropic. New correlations are therefore developed as part of this study1 to generalize the Sulem et al. equations by considering a non-homogeneous stress distribution (biaxial stress field) around the tunnel. The comparative results showed although the numerical results are very close to the analytical solution results, there is still a significant difference between the field data and analytical results.