Calibration of restitution coefficients using rockfall simulations based on 3D photogrammetry model: a case study

This paper presents a case study of an excavated rock slope to assess the coefficients of restitution using the results from field rockfall tests and corresponding rockfall simulations based on 3D photogrammetric slope surface models. The results from the field rockfall tests showed that rockfall trajectories were controlled by the orientations of joints at the initial point of the rockfalls. The lateral dispersion ratio (D (H)/L) of the trajectories was influenced by the shape index (gamma) of falling rocks as well. The directions of rockfall trajectories, which were obtained from the 3D simulation based on the 3D photogrammetric surface models, were in agreement with the field rockfall tests. Throughout 2D analysis, which was performed using predefined trajectories from the 3D simulations, the coefficients of restitution were successfully calibrated using elapsed times and distances obtained from the field rockfall tests. Based on the accurate 3D photogrammetric slope model, the back-calculated coefficients of restitution from the 3D and 2D simulations combined with field rockfall tests provided consistent results between the numerical analyses and the field experimental data.