Refined simulation for predicting the seismic collapse of high and steep dangerous rock masses via the 3D discrete element method

Considering the current challenges posed by steep mountain slopes and frequent seismic activity in the mountainous regions of Southwest China, alongside the pressing need for detailed investigations of hazards and risks on slopes and precise investigations of geological disasters in key towns, in this study, the limitations of two-dimensional simulations and nonseismic simulations are addressed. A more accurate and realistic method for earthquake-induced rockfall prediction is proposed. Refined models are built by combining airborne light detection and ranging (LiDAR) point clouds, dangerous rock mass morphologies and the structural plane orientations in rock masses. On the basis of the discrete element method and secondary development via the three-dimensional distinct element code (3DEC), an algorithm for evaluating three-dimensional discrete element earthquake-induced rockfalls is developed; this algorithm can more accurately predict earthquake-induced rockfalls by assessing the modes of collapse and destabilization, monitoring the collapse paths, judging the impacts, calculating the kinetic energy of the impacts, evaluating the disintegration of the dangerous rock mass and calculating the volume of the collapsed rock. In this study, the earthquake-induced collapse of a dangerous high-elevation rock mass in the hinterland of a county in Southwest China is predicted on the basis of the stability of the rock mass, destabilization patterns, falling paths, collapse volumes, impact energy, stopping locations and hazard ranges under different intensities and magnitudes of earthquakes, and suggestions for prevention and control are proposed. The results reveal that the zone of dangerous rocks in the study area is generally stable and partially unstable under static conditions. For earthquakes of intensity 9.0 and less, the zone of dangerous rocks was generally stable, but the overhanging dangerous rock mass at the top was less stable to unstable. In the Wenchuan Ms8.0 earthquake, the zone of dangerous rocks became unstable. The dangerous rock masses above and in front of the zone of dangerous rocks were prone to falling first, and the volume, deposition distance, kinetic energy, and threat to the hazard-affected body were positively correlated with the earthquake intensity. Therefore, the use of active avoidance measures in the study area should be prioritized to completely avoid collapse disasters caused by earthquakes. Additionally, a combination of proactive measures can be taken for management, emphasizing early prevention and control rather than relying primarily on passive measures. The research results can provide effective methods for predicting and preventing earthquake-induced rockfall disasters in the study area and other similar regions.