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Classical rockfall simulation models do not integrate the effect of coppice forest on bocks propagation. Although field observations and experimental tests have shown that coppice forest can play an important role of protection against rockfall hazard. In order to integrate coppice forest in rockfall modeling two models will be developed. The first one will generate a virtual coppice forest stands, the other will model the impact of a block against a coppice stem. To characterize the spatial organization of coppice forest and to develop a methodology to generate virtual coppice forest stands, dendrometric data have to be collected in forest with protection function. In a second time spatial point pattern analyses have to be carried out on the collected data in order to develop a model which automatically generates coppice forest structures using key dendrometic parameters. Second, the key issues in a numerical model of a block that impacts a clump in coppice forest are the definition of a “green wood” rheology material as well as the modeling of the contact between a block and a stem under dynamic loading. These issues will be tackled using laboratory experiments and a mechanical model of impact based on the discrete element method (DEM). Finally the two modules developed in this work: virtual coppice forest stand generation and impact modeling of a rock on a coppice will be integrated and validated in a 3D rockfall model.

On mountain slopes, forest can play an important role to protect human lives and facilities against rockfalls. Silvicultural strategies and interventions to maintain or improve protection forest structures are of first interest. Up to now, regional mapping of protection forest does not exist in France. The objectives of the study are to develop decision support tools for rockfall protection forest management. This paper present a Geographic Information Systems (GIS) based model which automatically maps forests with a protection function against rockfall hazard. This model, called RollFree, is a statistical based model which calculated maximum run out zone of rockfall based on the energy line principle. RollFree presents the advantages of a fast computational time and need only few input parameters such as a DEM, a map of the issues and a map of the forest cover. In the French region of Rhone-Alpes, results showed that forests with a protection function against rockfall can represent up to 30 % of all the forests in the district. These maps can be used as a decisional tool by practitioner to develop management strategies in order to define priority zones for more accurate rockfall mapping and adapted protection forest management.