Abstract
During an earthquake, fault slip weakening is often explained by
frictional heating phenomena, generally promoting melt production on the
fault surface. Here, we investigate the influence of melt production at
the scale of the grains composing a fault gouge. We use a modern version
of Discrete Element Modelling (DEM) able to deal with realistic grain
shapes, and couple it with a Multibody Meshfree Approach able to provide
a satisfactory proxy for the mechanical behaviour of molten grains.
Frictional sliding of solid grains and viscous shearing of molten grains
are monitored during simulations. Our results confirm the natural
tendency of granular gouge to localize deformation in a thin layer, and
thus to trigger local melt production. We also show that the appearance
of melt is likely to enhance this localization, and might create a
positive feedback to its own production. We propose guidelines for the
future writing of a friction model inspired by these simulation results.