5. Conclusion
We develop a physics-driven model
of interfacial friction for geomaterials. Our theoretical model
characterizes the random contact process of the interface through
porosity, which successfully captures the transition of mechanical
behavior from microscopic asperities to the macroscopic friction
interface. Our model reveals the
velocity-dependent sliding
friction behavior of these verified geomaterials and shows that the
interparticle contact temperature has a more dominant role in
velocity-dependent friction than the ambient temperature. The
velocity-dependent friction behavior can attribute to the adjustment of
stress state and property during high-velocity shearing. Meanwhile, the
difference in directional and tangential activation energy can cause
velocity-dependent strengthening or weakening effects for geomaterials.
The saturation of geomaterials not only exhibits the lubrication effect
but also shares part of the pore pressure, which contribute to the
decrease in the friction coefficient. Thus, the permeability and fluid
viscosity coefficients, which affect the water flow and distribution
characteristics, also affect the coefficient of friction.
These findings provide a further
understanding of the physical mechanism how shear velocity affect the
contact and sliding friction of geomaterials. It has important
implications for geological hazard prediction, not only in landslides
and earthquakes but also in glacial avalanches on earth, even sliding
failure progresses on other planets.