Abstract :
[en] Geomaterials are present in nature in many forms : solid soil or rock, soft clay, almost liquid
mud, etc. Geomechanics deals with the understanding the solid behavior of geomaterials.
However, solid ground can happen, under specific external conditions, to turn into fluid : as
for example during mudflows or debris flows. In such a context, our work concerns, in a general way, solid-fluid transition in geomaterials behavior and the
development of a constitutive model describing both the solid phase, fluid phase, and the
transition between the two. In this framework, we chose to carry out calculations with the
FEMLIP numerical method (Finite Element Method with Lagrangians Integration Points)
which has shown a strong potential to describe a wide variety of behaviors (including history
dependent behavior), in a unique model.
Having implemented and validated the first elasto-plastic law in Ellipsis (FEMLIP based
code), we have introduced in this code the solid-fluid transition model. This last is based on
the evolution, at the failure state detected by the second order work criterion, of the solid
elasto-plastic behavior towards a viscous fluid behavior, exhibiting a yield stress.
After validation of the solid-fluid transition model in homogeneous cases (considering Plasol
elasto-plastic law and Bingham viscous one), we applied this model to the modeling of Sarno
and Quindici mudflows (Italy, 1998).
