MPM SIMULATIONS OF GRANULAR COLUMN COLLAPSE WITH A NEW CONSTITUTIVE MODEL FOR THE SOLID-FLUID TRANSITION

Dry granular flows are very common both in many natural phenomena (flow-like landslides) as well as in industrial processes. To model granular flows in the framework of continuum mechanics, a key issue is the formulation of a suitable constitutive model, capable of capturing the complex rheological behaviour of the granular material in a wide range of strain rates. In this contribution, a physically based model capable of reproducing the behaviour of granular materials in different flow regimes is briefly summarized. Both the stress tensor and the dissipated energy are calculated as the sum of a quasi-static and a collisional contribution: the former one is modelled by employing an elasto-plastic model incorporating the critical state concept, whereas the latter stems from the kinetic theory of granular gases. The constitutive model has been implemented in the MPM research code Anura3D and applied to the simulation of the collapse of a dry granular column. The results show that the model can deal with the phase transition between the solid- and the fluid-like behaviour. The evolution of the state variables, the state of stress and the energy contributions is investigated in details.