Determining fragmentation of rock masses and their integration into propagation analysis.

There are numerous factors involved in rock fragmentation during a rockfall, making complex its modeling. The most relevant are the rock strength and the attitude and persistency of joints within the rock mass, energy absorption capacity of the ground, the total volume of detached rock and impact properties as the free fall height and angle of impact. Initially, the following objectives and hypothesis are defined:

- Development of techniques to know the block distribution “in situ”, in the rock cliff before rockfall event (In situ Rockfall Block Size Distribution, IBSD). These are based on the characterization of discontinuities in the rocky cliff on 3D models of the rock wall obtained by photogrammetric techniques. Unmanned Aerial Vehicles (UAV / drone / RPAS), that capture the necessary images, are used to cover areas of difficult access and reduce the risk associated with these fieldwork.

- To obtain block size distributions produced by rockfalls. Inventories of rockfall block size distribution generated in the rockfall deposit (Block Size Distribution Rockfall, RBSD) are measured, in order to compare it with the IBSD. This comparison can be used as an indicator of the degree of fragmentation produced. This comparison in different scenarios will identify the degree of relevance of each of the factors involved in the fragmentation.

- In situ rockfall tests carried out at quarries in order to obtain the speed, the number and size of the fragments generated. The obtaining of this information in real cases is very unusual.

- Development of a fragmentation module and its explicit incorporation into a 3D trajectories simulation software

References:

Matas G., Lantada N., Corominas J. , Gili J.A., Ruiz-Carulla R., Prades A. (2017). RockGIS: A GIS-based model for the analysis of fragmentation in rockfalls. Landslides. DOI.doi:10.1007/s10346-017-0818-7. Accepted: 13 March 2017 (in press). The final publication is available at Springer via http://dx.doi.org/10.1007/s10346-017-0818-7. Full Paper

Ruiz-Carulla, R., Corominas, J. and Mavrouli, O. (2015). Observed changes in the block size distribution as consequence of the rockfall fragmentation. In: EGU General Assembly 2015. Geophysical Research Abstracts, Vol. 17, EGU2015-15518,, Vienna. Abstract