Numerical solutions for tunnels excavated in strain-softening rock masses considering a combined support system

In this article, an alternative numerical procedure to calculate displacements and stresses of supported circular tunnels is proposed, considering the whole process tunnel advancement, sequential installation primary secondary support systems. derivation, plastic area rock mass divided into a large number annuli around tunnel, then Finite Difference Method employed. First, strain-softening behaviour model taken simulate post-failure mass. Furthermore, Mohr-Coulomb or Hoek-Brown failure criteria can be chosen, non-associated flow rule assumed dilatancy considered. After that, fictitious forces concept used thus, three-dimensional effect face Finally, solutions for supports obtained, by using compatibility conditions at both rock-support support-support interfaces. The results obtained from these agree well with those self-similar openings, were verified. proposed method has been compared convergence-confinement method. Parametric analyses are carried out investigate sensitivity selection. Then, application in design presented. provides convenient preliminary tunnels.