Phys.org June 11, 2024
Brittle deformation models commonly rely on Mohr-Coulomb plasticity coupled with prescribed softening of cohesion and/or friction with accumulated plastic strain. This captures fundamental properties of brittle failure, but is overly sensitive to empirical softening parameters that cannot be determined experimentally. Researchers in France designed a brittle constitutive law that captured key processes of brittle deformation, and could be straightforwardly implemented in standard geodynamic models. In the Sub-Critically-Altered Maxwell (SCAM) flow law the damage progressively and permanently weakened the rock’s elastic moduli, until cracks catastrophically interact and coalesce up to macroscopic failure. The model’s micromechanical parameters could be fully calibrated against rock deformation experiments. Upon implementing the SCAM flow law in 2-D plane strain simulations of rock deformation experiments, they found that it could produce Coulomb-oriented shear bands which originated as damage bands. They showed that SCAM models could be upscaled to simulate tectonic deformation of a 10-km thick brittle plate over millions of years. According to the researchers these features make the SCAM rheology a promising tool to further investigate the complexity of brittle behavior across scales… read more. Open Access TECHNICAL ARTICLEÂ
Experimental constraints on brittle rock strength as a function of increasing pressure… Credit: Geochemistry, Geophysics, Geosystems, 04 June 2024