THE FORMATION OF LABORATORY ANALOGUES OF NATURAL HYDRATE-BEARING FINE-GRAINED SOIL

William Smith, Jocelyn Grozic, Jeffrey Priest

In the proceedings of: GeoQuébec 2015: 68th Canadian Geotechnical Conference & 7th Canadian Permafrost Conference

Session: Laboratory Testing I / Essais en laboratoire I

ABSTRACT: Gas hydrates form in deep-water marine sediments, and have been suggested as being a geohazard when temperature or pressure changes result in hydrate dissociation, with fine-grained hydrate-bearing sediments posing the greatest potential risk. Recent drilling expeditions with improved sampling techniques have revealed that within fine-grained soils, hydrates form complex, sub-vertical veins. These veins are hypothesized to lead to an increase in the strength and stiffness of the hydrate-bearing soil. However, current understanding of the strength and deformation behaviour of hydrate-bearing sediments is limited to laboratory studies in which hydrate is formed within the pore space of sediments. This paper presents a detailed procedure in which vertical, cylindrical synthetic hydrate veins are formed within a consolidated laboratory-mixed fine-grained soil, and are then isotropically reconsolidated within a triaxial cell. Results indicate that hydrate veins remain intact throughout this process.

RÉSUMÉ: Les hydrates de gaz se forment dans les sédiments des fonds marins. Les sédiments à grains fins qui renferment des hydrates peuvent poser un risque si des changements de température ou de pression provoquent la fonte des hydrates. Des expéditions de forage ont révélé que les hydrates forment des veines complexes et sub-verticales dans les sédiments à grains fins. L'hypothèse est que ces veines causent une augmentation de la résistance et de la rigidité du sédiment. Cependant, notre compréhension de la résistance et du comportemtent en déformation des sédiments contenant des hydrates est limitée à des études en laboratoire lors desquelles les hydrates se forment dans les pores du sédiment. Cet article présente une procédure détaillée pour former des veines synthétiques verticales et cylindriques d'hydrates dans un sédiment à grain fin. Les échantillons sont ensuite reconsolidés sous pression isotrope dans une cellule triaxiale. Les résultats indiquent que les veines hydrates restent intactes tout au long de la procédure.

Access this article:
Canadian Geotechnical Society members can access to this article, along with all other Canadian Geotechnical Conference proceedings, in the Member Area. Conference proceedings are also available in many libraries.

Cite this article:
William Smith; Jocelyn Grozic; Jeffrey Priest (2015) THE FORMATION OF LABORATORY ANALOGUES OF NATURAL HYDRATE-BEARING FINE-GRAINED SOIL in GEO2015. Ottawa, Ontario: Canadian Geotechnical Society.

@article{655,author = William Smith; Jocelyn Grozic; Jeffrey Priest,title = THE FORMATION OF LABORATORY ANALOGUES OF NATURAL HYDRATE-BEARING FINE-GRAINED SOIL,year = 2015}