Unconventional effective stress: concept and applications

Coal seams are promising for energy storage and CO2 sequestration. Experiments show that coal properties, including permeability and Young’s modulus, evolve during gas adsorption in ways that the conventional effective stress (CES) theory cannot predict. This thesis resolves the gap by proposing unconventional effective stress (UES), which unifies sorption-induced processes through a “fictitious stress” quantifying self-constrained or facilitated swelling. Constitutive models built on UES reproduce observations. Embedded in a coupled multi-component hydro-mechanical dual-porosity framework, these models assess symbiotic hydrogen–CO2 storage, demonstrating that UES captures property evolution and informs practical strategies for large-scale hydrogen storage with simultaneous CO2 sequestration.