Physical modelling to better understand rock avalanches

Several authors have resorted to physical modelling in the field of rock avalanches. After a review of some of these works, the present paper describes tests carried out at the Ecole Polytechnique Fédérale de Lausanne. The main goal of these experiments, i.e. unconstrained flows of gravel and blocks, is to better understand propagation mechanisms and to identify parameters influencing rock avalanche deposit characteristics. The use of new measuring techniques and of bricks that can be arranged orderly allows studying parameters such as the structure of the mass before failure, which was not considered before and resulted to have a relevant influence on propagation. This underlines that, despite the difficulty in matching the scaling laws, observation of experiments contributes in highlighting new aspects of complex phenomena and in better understanding mechanisms likely to happen at large scale and it confirms that physical modelling is an essential tool in rock avalanche study.