The main feature is that the mass descends very rapidly through the air by falling, bouncing, and rolling. Rockfalls are defined as the detachment of a rock from a steep slope along a surface on which little or no shear displacement takes place (Cruden and Varnes 1996). This type of events may be mitigated with stabilization and protection works but often engineers have to make difficult judgements due to the uncertainties associated to the prediction of the size and frequency of the potential events. Recent studies (Petley 2012) have shown that losses due to landslides and rockfalls are concentrated in less developed countries in which deficit of research exists, and often lack of the appropriate resources. Turner and Jayaprakash ( 2012) prepared an exhaustive list of rockfall events which demonstrates that even relatively small volumes of rocks may cause significant damage and traffic disruption, particularly in railroads. Although rockfalls have a limited size, they are extremely rapid processes that exhibit high kinetic energies and damaging capability. The unpredictable nature often attributed to the rockfalls events is cause of concern of the authorities and decision makers. Although most of them take place in remote places, they also threaten residential areas and transport corridors (Hungr et al. Rockfalls are widespread phenomena in mountain ranges, coastal cliffs, volcanos, river banks, and slope cuts. Finally, the performance of a fractal fragmentation model for rockfalls is also discussed. The extrapolation of the magnitude-frequency relationships is discussed as well as the role of the geological factors for constraining the size of the largest detachable mass from a cliff. Several case studies of the application of the remote acquisition techniques for determining the size and frequency of rockfall events and their fragmentation are presented. The latter is a crucial issue as it affects the number, size and the velocity of the individual rock blocks. The analysis of rockfalls must consider not only the frequency and magnitude of the potential events but also the fragmentation of the detached rock mass. The quantitative analysis of the fragmental rockfalls is a useful approach to assess risk and for the design of both stabilization and protection measures. These techniques are also used to monitor the deformation experienced by the rock mass before failure. The prediction of the occurrence and frequency of the rockfalls has benefited by the rapid development of the techniques for the detection and the remote acquisition of the rock mass surface features such as the 3D laser scanner and the digital photogrammetry. This contribution focuses on fragmental rockfalls in which the moving particles, particularly the largest ones, propagate following independent paths with little interaction among them. Rockfalls are very rapid and damaging slope instability processes that affect mountainous regions, coastal cliffs and slope cuts.

Scar stock crack forum