Influences of hydrate morphology and hydrate distribution heterogeneity on the mechanical properties of hydrate-bearing sediments using the discrete element method

The presence of gas hydrates in sediments affects the interaction between hydrate and sediment particles, which is associated with the most fundamental aspect of the mechanical behavior of hydrate-bearing sediments (HBS). The discrete element models of HBS with pore-filling, cementing, and load-bearing hydrates are proposed. In addition, homogeneous and heterogeneous distribution modes of hydrates are considered for the three hydrate morphologies. A series of triaxial compression test simulations are carried out to investigate the influences of hydrate morphology and hydrate distribution heterogeneity on the mechanical properties of hydrate-bearing sediments. The simulation results reveal that hydrate morphology can significantly while hydrate distribution heterogeneity can slightly affect the macro and micromechanical properties. Heterogeneous HBS shows a larger shear strength than homogeneous HBS. The cementing type of HBS exhibits the largest mid-strain modulus among the three hydrate morphologies. Sediment-sediment contacts contribute the most, while hydrate-hydrate contacts contribute the least to the shear strength regardless of hydrate morphology and hydrate distribution heterogeneity. It is also found that the cracks that occurred in HBS specimens depend on hydrate morphology and distribution heterogeneity. These findings are helpful to establish an accurate constitutive model for the HBS with a complex distribution of hydrates. Article Highlights Hydrate morphology significantly affects the mechanical properties of hydrate-bearing sediments. Heterogeneous hydrate-bearing sediments exhibit a larger shear strength than homogeneous ones. Sediment-sediment contacts primarily contribute to the shear strength of hydratebearing sediments.