Objective 2: Validation of the fragmentation model

During the development of the Rockrisk project, the research group has prepared a fractal fragmentation model, based on the ideas of Perfect (1997), and improved with the incorporation of the IBSD and a block survival factor (Ruiz-Carulla 2015b). This model allows to obtain the distribution of volumes of the blocks or fragments (RBSD) detached from a single initial block or an IBSD.

The new RBSD depends on the fractal dimension, on the number of initiators, the survival index of the blocks and the number of iterations. Our conclusions, so far, are that the fractal dimension depends on the characteristics of the initial rock mass; the number of IBSD initiators; the survival rate, the free height of the fall (impact energy) and the dimensions of the initial mass (the larger the volume); while the number of iterations reflects the degree of conminution experienced by the rock mass in its fall. Each of these parameters moves between a range of limited values. Until now, the values of the model parameters have been obtained through adjustments until the IBSD becomes the RBSD.

The objective 2 of this project is be able to assign "a priori" (before the cliff failure) and through calibration, the coefficients of the model based on the type of rock, type of substrate and geometry of the slope and anticipate ("forward prediction”) the volume distribution of fragments resulting from detachment.