Interaction of circular tunnels in anisotropic elastic ground

The problem of a single tunnel in anisotropic ground has been largely studied in the literature but the interaction of two tunnels is mostly addressed for the isotropic case. Simple superposition of the solutions of two non-interacting tunnels may give reasonable results if the distance between the tunnels is large enough, but fails when the tunnels are excavated close to each other. Based on complex variable theory, closed-form solutions for the stresses and displacements around two deep circular tunnels in a homogeneous, transversely isotropic and linear elastic ground with non-isotropic far-field stress conditions are developed. The results obtained with the proposed analytical solution are compared with those obtained with the numerical code Flac3D. The effects of the orientation of the isotropic plane and of the distance between two tunnels on the stress and displacements fields are discussed.