Recent advances in creep behaviors characterization for hydrate-bearing sediment

Natural gas hydrate (NGH) is widely accepted as one of the promising sustainable energy resources, whereas the potential geo-engineering risks have become one of the major uncertainties during long-term NGH exploitation. Creep is one of the primary inducements of geo-engineering risks during the long-term exploitation of marine gas hydrates. To understand the current research progresses on the creep behaviors of hydrate-bearing sediments (HBS), this paper summarized laboratory mechanical testing techniques, sensitive analysis, and constitutive models for the creep of HBS. The results showed that triaxial testing plays a leading role in the creep testing of HBS. From the micron perspective, the atomic force microscopy has great potential in determining the creep behaviors of HBS. The current publications reveal that the creep process of HBS under a lower loading may not always experience the initial creep stage, stable creep stage, and reach to accelerated creep stage. The previous studies provide a macroscopic understanding of the mechanical testing method and constitutive model, which is beneficial to the numerical simulation of the ground deformation of HBS during hydrate exploitation. However, the existing constitutive models are far from satisfying the demand for numerical simulations and field applications on the creep behavior of HBS. Developing a creep model by referring to the constitutive creep model of frozen soil is anticipated to be more feasible.