Particularly the soil–infilled rock joints have a dominant role in controlling the stability of the wedge block due to its reduced friction and cohesion (Indraratna et al., 2010). Roof failure occurs when the base of the wedge is fully exposed by the excavation of the opening. For sidewall wedges, sliding of few millimeters along one plane or along the line of intersection of two planes is generally sufficient to overcome the peak strength of these surfaces (Akgun et al.,
2014). The wedge analysis was done by Unwedge software v.1.0(Rocscience, 2004) using the joint data. The operational steps of the Unwedge software are given in Appendix I(b).