Unified Model for Geomaterial Solid/Fluid States and the Transition in Between

AbstractDuring mudflows, geomaterials evolve in a very specific manner, because initially they behave as solids, and then they turn to flow as viscous fluids. This paper proposes an original approach to simulate, within a single numerical framework, such a transition between a solid-like and a fluid-like behavior. The model used is based on the association of an elastoplastic and a viscous constitutive relation to describe both phases of the behavior. The transition between the two is assumed to correspond to a failure state, and the transition criterion considered is thus based on the general second-order work stability criterion. The Plasol elastoplastic model and the Bingham viscous model are used because they are suitable to describe soils and granular suspensions, respectively. In this preliminary study, the global model is tested for two homogeneous loading paths with drained and undrained conditions. For these cases, the radical transformation of the material behavior at failure is captured, and both the solid-to-fluid and the fluid-to-solid transitions are consistently enabled, making possible future applications of this approach for gravitational flow modeling.