“…These simplified models having been validated by direct shear tests performed under constant normal load conditions (CNL), for certain load conditions. However, parameters such as the presence of infill material and also normal stiffness caused by the surrounding rock mass or rock bolts, which significantly influence the shear strength of the discontinuities are not considered (Ladanyi & Archambault, 1977;Papaliangas et al, 1993;Haque, 1999;Haque & Indraratna, 2000;Indraratna et al, 1999Indraratna et al, , 2005Indraratna et al, , 2010Indraratna et al, , 2012Indraratna et al, , 2013Indraratna et al, , 2014Indraratna et al, , 2015Oliveira et al, 2009;Naghadehi, 2015;Karakus et al, 2016;Mehrishal et al, 2016;Shrivastava & Rao, 2017). On the other hand, the use of analytical models for rationally considering the effect of the infill and the normal stiffness of the rock discontinuities is hampered by the number of parameters required.…”