Discrete dynamic modelling of the mechanical behaviour of a granular soil

Lingran Zhang (1) , Stéphane Lambert (2) , François Nicot (2)

1 IRSTEA - Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture
2 UR ETGR (ETNA) - Erosion torrentielle neige et avalanches

This paper investigates the interaction between a falling rock boulder and a granular medium through numerical modelling based on a discrete element method. The boulder is modelled as a single sphere with an incident velocity, and the medium is modelled as an assembly composed of poly-disperse spherical particles. A classical elastic-plastic contact law is implemented with rolling resistance to consider the particle shape effects. The numerical modelling is validated by comparison with results from the literature in terms of impact force, impact duration and the boulder's penetration depth of the boulder. Then the model is used to investigate the energy propagation within the impacted medium as well as the boulder bouncing. The energy propagation processes are investigated by analysing the space distribution of kinetic energy, elastic strain energy and energy dissipation within the medium over time. The boulder bouncing occurrence is studied, varying the impact conditions in terms of medium thickness and boulder size. Relations between the bouncing of the boulder and the response of the granular medium are finally discussed.

Mots clés: Discrete element method; Kinetic energy; Granular material; Impact; Rockfall

Domaines: Géotechnique

Lingran Zhang, Stéphane Lambert, François Nicot. Discrete dynamic modelling of the mechanical behaviour of a granular soil. International Journal of Impact Engineering, 2017, 103, pp.76-89. ⟨10.1016/j.ijimpeng.2017.01.009⟩. ⟨hal-01987529⟩