A rate-, state-, and temperature-dependent friction law with competing healing mechanisms

Sylvain D. Barbot

Submitted September 11, 2022, SCEC Contribution #11918, 2022 SCEC Annual Meeting Poster #127

The constitutive behavior of faults is central to many interconnected aspects of earthquake science, from fault dynamics to induced seismicity, to seismic hazards characterization. Yet, a friction law applicable to the range of temperatures found in the brittle crust and upper mantle is still missing. In particular, rocks often exhibit a transition from steady-state velocity-strengthening to velocity-weakening with increasing temperature that is poorly understood. Here, we investigate the effect of competing healing mechanisms on the evolution of frictional properties in a physical model of rate-, state-, and temperature-dependent friction. The yield strength depends on the real area of contact, which is modulated by the competition between the growth and erosion of interfacial micro-asperities. Incorporating multiple healing mechanisms and rock-forming minerals with different thermodynamic properties allows a transition of the velocity- and temperature-dependence of friction at steady-state with varying temperatures. We explain the mechanical data for granite, pyroxene, amphibole, shale, and natural fault gouges with activation energies and stress power exponent for weakening of 10-50 kJ/mol and 55-150, respectively, compatible with subcritical crack growth and inter-granular flow in the active slip zone. Activation energies for the time-dependent healing process in the range 90-130 kJ/mol in dry conditions and 20-65 kJ/mol in wet conditions indicate the prominence of viscoelastic collapse of micro-asperities in the absence of water and of pressure-solution creep, crack healing, and cementation when assisted by pore fluids.

Key Words
friction, constitutive law, thermodynamics

Citation
Barbot, S. D. (2022, 09). A rate-, state-, and temperature-dependent friction law with competing healing mechanisms. Poster Presentation at 2022 SCEC Annual Meeting.

Related Projects & Working Groups
Fault and Rupture Mechanics (FARM)