Influence of gassy soils and gas hydrates on submarine slope failure

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Offshore geohazards impact the economic development and safe operation of marine infrastructure.  Landslides occurring on the ocean floor are a common geohazard that have considerable potential for damage and loss of life; yet, the triggering and evolution of submarine slides is not well understood.  This is particularly true when examining the effects of gas in soils.  Gas, in bubble or hydrate form, has been circumstantially and theoretically linked to many submarine slope failures.  However, it remains a major challenge to integrate the role of gas into the quantitative analysis and prediction of submarine slope failures. This research is aimed at obtaining an integrated understanding of the significance of gas in marine soils using a combined experimental and theoretical approach.  Experimental studies will investigate the fundamental behaviour of soil containing gas and gas hydrates using customized geotechnical testing equipment located in two new facilities at the University of Calgary.  Constitutive models, verified with the results of the laboratory program, will be developed to describe the theoretical behavioural changes of the soil during hydrate dissociation and gassy soil unloading.  The constitutive models will then be incorporated into stability assessments to quantitatively analyze the stability of submarine slopes.  Finally, the results from all phases will be synthesized to develop recommendations regarding submarine slope stability, with particular emphasis on the governing parameters such as gas content, hydrate content, soil conditions, topography, and oceanographic data.  These recommendations will ultimately result in the development of guidelines that will enable the risk of damage to existing infrastructure and coastal developments to be evaluated and facilitate safer and more cost-effective designs of future offshore developments.  As the search for resources takes us into deeper water, remote regions, and unfamiliar territory, and the expanding global population continues increasing pressure to already burgeoning coastal areas, improved knowledge of the seabed conditions is of critical importance.