About this Research Topic
Degradations, bifurcations and instabilities in geomaterials (soils, rocks, concrete) have attracted the interest of a nowadays well recognized scientific community. Several facets of this topic have been investigated in the past, from the experimental characterization of strain localization (shear bands, compaction bands) and the micromechanics of instabilities in granular materials, to the formulation of enriched continuum theories capable to provide the mathematical framework for treating loss of uniqueness and loss of stability of homogeneous solutions, and the development of numerical techniques able to capture the multiple (finite) solutions of a finite element discretized problem. The purpose of this Research Topic is to extend this fruitful combination of experimental, theoretical and numerical approaches to the study of coupled hydromechanical instabilities, where the notion of mechanical instabilities is enriched by the complementary (and not necessarily independent) notion of hydraulic instabilities, with a key role played by interfaces and coupled hydromechanical phenomena.
Geomaterials are intrinsically multi-phase materials, the porous network being typically saturated by a mixture of fluids. Therefore, degradations and instabilities can manifest both in the solid and in the fluid phases. As a consequence, localized or diffuse scale instabilities as well as grain remodeling, at the meso and microscopic scale of the porous skeleton, can obviously affect the behavior of the fluid phase, inducing heterogeneous and anisotropic fluid flow through the material. However, the reverse is also true: fluid instabilities, at different scales, as Haines jumps, fluid pinch-off, fingering, etc. can affect the mechanical response of the solid phase inducing strain localization and heterogeneous remodeling. Investigating instabilities in geomaterials is therefore of paramount importance in order to understand the role of interfaces between the solid and fluid phases.
We plan to tackle the above-mentioned challenges addressing them from different angles, and investigating the response of geomaterials both at the microscopic pore scale and at the mesoscopic scale of laboratory samples.
The field of applications is expected to be wide enough to range from underground energy storage (gas storage, heat storage, …), CO2 geological sequestration, fault reactivation, artificially induced and natural seismicity, nuclear waste disposal, etc.
Contributions in experimental mechanics and interface detection, which take advantage of non-destructive imaging techniques, as well as in continuum and discrete poromechanics, modeling of interfaces and numerical simulation will be solicited.
The following themes identify a (non-exhaustive) list of specific topics which the editors would like the contributors to address:
• Hydro-mechanical coupled instabilities in geomaterials
• Fingering and remodeling in unsaturated porous media
• Phase-field modeling in unsaturated porous media
• Lattice approach for modeling hydraulic fracture and multi-phase flow in porous media
• Fluid−fluid displacement in porous media: pore scale mechanisms
• Fingering patterns in multi-scale porous media
• Interfaces detection and tracking
• Level-set methods
• Non-destructive imaging techniques
• Discrete and Finite Element methods
Keywords: hydromechanical instabilities, Geomaterials
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