Analysis of tunnel support requirements using the convergence-confinement method and the hoek-brown rock failure criterion

This paper discusses the application of the Convergence-Confinement method of tunnel design to rock masses that are assumed to obey the Hoek-Brown failure criterion. The basis of the Convergence-Confinement method and the interpretation of the three basic components of the method the Longitudinal Deformation Profile (LDP), the Ground Reaction Curve (GRC) and the Support Characteristic Curve (SCC) are presented. A closed form solution for the construction of the GRC considering a general form of the Hoek-Brown failure criterion for rock is presented. An example illustrating the application of the solution to the construction of the GRC using the closed-form solution is discussed and results compared with those from the classical Hoek-Brown criterion as implemented in the finite difference code FLAC^3D