Kinectic energy dissipation effects of rock fall attenuating systems

[Departement_IRSTEA]Territoires [TR1_IRSTEA]SEDYVIN

International audience

English. Attenuation, is the reduction in intensity of any flux through a medium. Rock fall attenuator systems are structures made of flexible wire netting designed reduce the intensity (kinetic energy) of rock fall and guide their trajectory. In order to evaluate the protective effect of an attenuating system and their capacity to absorb high energy impacts, high speed video recording methods have been applied to capture full scale rock rolling and attenuator barrier tests. The application of video methods requires that individual frames are scaled to the plane of the rock fall. Following this the rock fall trajectory and velocity over time can be extracted from the video. Herein, an assessment of the error in different approaches to video image scaling and position tracking for video analysis is made. Additionally the trajectories and velocity of rock falls from both un-attenuated rock rolling experiments and experiments testing the rock fall attenuator systems are analysed. A comparison of these data has allowed an assessment of the energy absorbed by the attenuator systems. Additionally, restitution coefficients for impacts on hard rock slopes have been drawn from the data, assisting in a simple model applied to estimation the attenuation effects of rock fall attenuator systems.