Modeling hydrate-bearing sediment with a mixed smoothed particle hydrodynamics

Marine gas hydrate is an important energy source while its extraction may induce environmental problems such as subsea landslide, which is usually challengeable for numerical simulation due to the marine environment with high pressure and the existence of gas hydrate. Smoothed particle hydrodynamics (SPH) is a Lagrangian particle method which is attractive in modeling problems with large deformations and fluid–solid interactions (FSI) for continuum and granular materials. However, the conventional SPH suffers from numerical instability when modeling the soil mechanics with the high confining stress. A mixed SPH is developed in this study to simulate hydrate-bearing sediment with the characteristics of high confining stress. In the mixed SPH model, the conventional SPH is used to discretize the momentum equations, and the kernel gradient correction (KGC) SPH is used to discretize strain and spin rate tensors. In order to consider the effect of hydrate saturation on the strength of soil-hydrate material, an existing linear model is applied into the mixed SPH to define the mechanic parameters of soil-hydrate material. The mixed SPH method is validated by several examples and the obtained numerical results are in close agreement with experimental observations. Finally, the mixed SPH method is used to model landslide of hydrate bearing sediments. The results show that the saturation of hydrate has important impact on the stability of hydrate bearing sediments.