Discussion of the paper: ‘Rock nail reinforcement of a free surface’ by Euripides Papamichos and Ioannis Vardoulakis, International Journal for Numerical and Analytical Methods in Geomechanics 2010. DOI: 10.1002/nag.1003

The paper by Papamichos and Vardoulakis represents a contribution to the mechanical modelling of a rock material reinforced by the introduction of metallic bolts or nails, with a special emphasis on the way the interactions between the nails and the rock may be captured by means of a specific constitutive law. Leaving aside Section 2, which is devoted to the analysis of a single nail embedded in a rock specimen subject to plane-strain compression, our comments and criticisms will be focused on Section 3 (and secondarily Section 4), where the compression of a rectangular block of rock reinforced by an array of regularly distributed nails, is considered.