Comprehensive review of geomechanical constitutive models of gas hydrate-bearing sediments

Natural gas hydrates (NGHs) are regarded as a promising energy resource. To quantitatively analyze the response of gas hydrate-bearing sediments (GHBSs) under stress during NGHs exploitation, it is essential to establish geomechanical constitutive models of GHBSs that describe their strength and deformation characteristics. Geomechanical constitutive models of GHBSs have been established for describing mechanical behavior of the GHBSs and typically consider the influences of hydrate saturation and hydrate accumulation habits on the mechanical properties based on the constitutive model of soil. This paper reviews most available and widely used geomechanical constitutive models of GHBSs, including nonlinear elastic models, models based on MohrCoulomb criterion, critical state models, time-dependent models and other types of models. In addition to summarizing the characteristics of the models in detail, the advantages and limitations of each model were discussed, and insightful suggestions regarding establishing new models were provided. This paper may provide guidance for the establishment of new geomechanical constitutive models and for the numerical simulation of the ground deformation of GHBSs during hydrate exploitation.