A numerical large strain solution for circular tunnels excavated in strain-softening rock masses

This paper presents a large strain numerical solution of a circular tunnel for the ground reaction curve (GRC) in strain-softening rock masses. Both the stress equilibrium equation and deformation compatibility equation are considered in a current coordinate. A series of examples are employed to validate the proposed solutions, and the results show that: (1) the displacement, softening and residual radii of larger strain solution are smaller than that of small strain solution, and their difference significantly increases with a decrease in the Young's modulus. (2) the increasing Poisson's ration and critical shear plastic strain decrease the displacement, softening and residual radii.