Predicting the Yield Stress of Geomaterials from Their Microstructure

The seminal work of Gurson (J Eng Mater Technol 99:2–5, 1977) on a simplified pore structure, a single spherical pore, first provided a theoretical relationship between the yield stress and the porosity. This contribution extends the approach to determine the macroscopic yield of a porous material by taking explicitly into account its...

Reconciling asymmetry observations in the permeability tensor of digital rocks with symmetry expectations

Modelling anisotropic flow in rocks requires their full permeability tensor. While theories derived from the upscaling of Stokes flow to Darcy's law may justify the tensor symmetry, homogenisations from micro-scale rock samples often return a non-zero level of asymmetry. Since most studies dismiss these controversial observations as numerical...

Experimental evidence that viscous shear zones generate periodic pore sheets

In experiments designed to understand deep shear zones, we show that periodic porous sheets emerge spontaneously during viscous creep and that they facilitate mass transfer. These findings challenge conventional expectations of how viscosity in solid rocks operates and provide quantitative data in favour of an alternative paradigm, that of...

Dynamic Recrystallization Can Produce Porosity in Shear Zones

Creep cavities are increasingly recognized as an important syn-kinematic feature of shear zones, but much about this porosity needs investigation. Largely, observations of creep cavities are restricted to very fine grained mature ultramylonites, and it is unclear when they developed during deformation. Specifically, a question that needs...