Discussion on ''Seismic displacement along a log-spiral failure surface with crack using rock Hoek-Brown failure criterion''

This discussion is based on the paper by Zhao et al. [4] (hereafter identified as “the authors” or “the original paper”). In the original paper, the authors presented a numerical model to calculate the seismic displacement for rock slopes with cracks using the Hoek-Brown yield criterion. For the proposed numerical model, the upper bound limit analysis and rigid block displacement technique were employed in which the actual horizontal and vertical earthquake ground motion records were utilized in the analyses. This discussion addresses the theoretical issues of the computed permanent seismic displacements in conjunction with the upper bound limit analysis using the rigid block displacement technique. In addition, the discussion comments on some issues related to the assumption of using the factor of safety being less than 1 for a calculation of induced seismic displacement under an actual time history of horizontal and vertical accelerations, and the use of fixed crack depth ratios of 0.1 and 0.2 in the parametric studies of the original paper.