Application of the Convergence-Confinement method of tunnel design to rock masses that satisfy the Hoek-Brown failure criterion

This paper discusses the practical application of the Convergence-Confinement Method of tunnel design to rock-masses that satisfy the Hoek-Brown failure criterion. The strength of intact rock and jointed rock-masses, as defined by the Hoek-Brown criterion, and the basis of the Convergence-Confinement method are reviewed. Equations that allow the construction of the three basic components of the Convergence-Confinement method, i) the Longitudinal Deformation Profile (LDP), ii) the Ground Reaction Curve (GRC) and iii) the Support Characteristic Curve (SCC) are given. A practical case of support design for a circular tunnel is discussed and solved using the Convergence Confinement method. A spreadsheet summarizing the implementation of the method is also included. Reference values of typical rock properties and geometrical and mechanical properties for typical support systems are presented in tables and charts.