Modelling Recurrent Stress Drops in Porous Media

Abstract

Abstract Brittle porous media subjected to confined compression experience rate-dependent compaction behaviour ranging from smooth stress-strain to one with recurrent abrupt drops in stress. Micromechanical investigations suggest that stress drops correlate with the collapse of the meso-scale structure. As such, we develop a novel model that qualitatively generates such behaviour. A vital feature of the model is the meso-related temperature, which characterises the fluctuating velocities at the meso-scale and, importantly, in general to all heterogeneous porous media. We assume that such temperature induces a loss of strength at the macro-scale and leads to a stress drop. Additionally, the meso-related temperature decays into micro-related (thermal) temperature, thus allowing stress to recover following a stress drop. Our model exhibits the different stress drop regimes and provides insight into the physical mechanisms required to generate these compaction patterns in brittle porous media.KeywordsPorous mediaStress dropsRate-dependentMeso-scale