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The dependence of rock behavior on the deformation rate is still not well understood. In salt rock, the fundamental mechanisms that drive the accumulation of irreversible deformation, the reduction of stiffness, and the development of hysteresis during cyclic loading are usually attributed to intracrystalline plasticity and diffusion. We hypothesize that at low pressure and low temperature, the rate‐dependent behavior of salt rock is governed by water‐assisted diffusion along grain boundaries. Accordingly, a chemo‐mechanical homogenization framework is proposed in which the representative elementary volume (REV) is viewed as a homogeneous polycrystalline matrix that contains sliding grain‐boundary cracks. The slip is related to the mass of salt ions that diffuse along the crack surface. The relationship between fluid inclusion‐scale and REV‐scale stresses and strains is established by using the Mori–Tanaka homogenization scheme. It is noted from the model that a lower strain rate and a larger number of sliding cracks enhance stiffness reduction and hysteresis. Thinner sliding cracks (i.e., thinner brine films) promote stiffness reduction and accelerate stress redistributions. The larger the volume fraction of the crack inclusions, the larger the REV deformation and the larger the hysteresis. Results presented in this study shed light on the mechanical behavior of salt rock that is pertinent to the design of geological storage facilities that undergo cyclic unloading, which could help optimize the energy production cycle with low carbon emissions.

Bedrock weakening is of wide interest because it influences landscape evolution, chemical weathering, and subsurface hydrology. A longstanding hypothesis states that bedrock weakening is driven by chemical weathering of minerals like biotite, which expand as they weather and create stresses sufficient to fracture rock. We build on recent advances in rock damage mechanics to develop a model for the influence of multimineral chemical weathering on bedrock damage, which is defined as the reduction in bedrock stiffness. We use biotite chemical weathering as an example application of this model to explore how the abundance, aspect ratio, and orientation affect the time‐dependent evolution of bedrock damage during biotite chemical weathering. Our simulations suggest that biotite abundance and aspect ratio have a profound effect on the evolution of bedrock damage during biotite chemical weathering. These characteristics exert particularly strong influences on the timing of the onset of damage, which occurs earlier under higher biotite abundances and smaller biotite aspect ratios. Biotite orientation, by contrast, exerts a relatively weak influence on damage. Our simulations further show that damage development is strongly influenced by the boundary conditions, with damage initiating earlier under laterally confined boundaries than under unconfined boundaries. These simulations suggest that relatively minor differences in biotite populations can drive significant differences in the progression of rock weakening. This highlights the need for observations of biotite abundance, aspect ratio, and orientation at the mineral and field scales and motivates efforts to upscale this microscale model to investigate the evolution of the macroscale fracture network.