A fully coupled multi-physics THCM model for the marine hydrate-bearing sediment

Purpose A fully coupled multi-physics model is established to simulate thermal, hydraulic, chemical and mechanical (THCM) behaviors of the sediments with the hydrate dissociation. Design/methodology/approach Linear hydrate-soil constitutive model; Mohr–Coulomb yield criterion; Thermal, hydraulic and chemical (THC) model. Findings (1) The linear internal friction angle model proposed in this study can more reasonably simulate the effect of hydrate saturation on the mechanical properties of sediment than the fixed internal friction angle model. (2) The established THCM model can not only accurately simulate temperature variations and gas production efficiency but also reasonably simulate effective stress reduction and volumetric contraction of sediment during the process of hydrate dissociation. (3) The dissociation of hydrate not only decreases the instability coefficient of sediment but also increases the moving distance and equivalent plastic strain of the sediment. Research limitations/implications The hydrate sediment with large deformations should be considered in the future. Practical implications The submarine landslide will be investigated in the future. Originality/value (1) A linear hydrate-soil constitutive model based on the Mohr–Coulomb yield criterion is proposed, which defines the internal friction angle, the elastic modulus and the cohesion as a linear function of hydrate saturation. (2) A fully coupled multi-physics THCM model is established to simulate thermal, hydraulic, chemical and mechanical behaviors of hydrate-bearing sediment.