Multiphysics of Fluid-Saturated Geomaterials and Chemically Damaged Barriers

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*This research will develop innovative experimental techniques and theoretical models of coupled processes in geomaterials and implement the approaches in computational schemes that can examine and predict the outcome of geologic disposal and containment strategies important to energy resources recovery, nuclear waste management, geologic sequestration of greenhouse gases and geothermal energy extraction. The role of multiphysics couplings needs to be understood in the context of the interaction of thermal (T), hydraulic (H), mechanical (M) and chemical (C) processes. The emphasis of the research program is to achieve the necessary advances in theoretical, computational and experimental procedures that have immediate applications to geoenvironmental protection strategies. ***The highly heterogeneous Cobourg Limestone, targeted by the Nuclear Waste Management Organization, ON, for deep geological storage of radioactive wastes, will be studied using large cylindrical samples (150 mm dia., 300 mm long). The internal features of the rock present a challenge in terms of multi-scale coupled processes and for this reason, experiments will be performed using the recently acquired Triaxial Cell with Acoustic Emission Tomography mapping capabilities, to progressively track defect evolution that will affect the THM responses. This equipment is unique to Canada. Using the experimental results, reliable models of the THM behaviour of Cobourg Limestone will be achieved to predict the long-term scenarios of NWMO initiatives. ***The research will also examine THMC effects in geologic storage of CO2 in carbonate reservoirs since the targeted storage horizons in Canada are largely carbonate rocks. Preliminary studies reveal that wormholes or dissolution channels develop rapidly in carbonate-rich samples; this will affect the storage potential of the aquifer and compromise the structural support that provides stability for caprock barriers. Storage rocks from Weyburn, SK, Brooks, AB and Bécancour, QC will be tested and models developed to relate chemical erosion at fractures and sealing interfaces to alterations in geostatic stress states and carbonate content. ***Research will also address the role of chemicals on the mechanics of geosynthetics, particularly their embrittlement due to plasticizer removal, and examine the stress-assisted transport of chemicals in geomembranes leading to anisotropic effects. Rate-sensitive constitutive models will be developed; these could be used to predict tearing failure at defects, at connecting seams and, in particular, the localized regions of action of chemicals such as ethanol. ***Over the next five years, the research program will train PDFs, PhDs, Masters and UG students, with skills to effectively contribute to these areas. The projects will have a significant impact on the development of policy for the protection of the environment. **