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Geological disposal facilities (GDFs) rely on engineered barrier systems to isolate radioactive waste from the biosphere over a timescale extending to one million years. Bentonite and cement have become popular barrier materials while the authors suggest that quick clay could also be a suitable material.
Quick clay, a marine clay, is characterised by its extreme thixotropic behaviour and plastic deformation properties. There is a possibility of using quick clay to create barriers for GDF boreholes and shafts that will produce less CO2 and accommodate likely fatigue-creating cyclical loading caused by incessant twice-daily earth tides acting during the one million year GDF design life.
Potential advantages of applying quick clay as a deformable barrier material are considered within the framework of an engineered barrier system with performance requirements for shafts and wells, designed with a view to meeting the GDF challenges – extreme longevity and minimal CO2 production. Particular attention is paid to the cyclical loading applied to the barrier by earth tides, invoking the resistance of barrier materials to loading twice per day by earth tides, which could cause failure of rigid materials such as cement in a fatigue mode.