A bounding surface model of gas-hydrate-bearing sediments

Gas hydrates are a very promising energy source, but its exploitation also faces some challenges in marine geotechnics. The dissociation and formation of hydrates can significantly change the mechanical properties of sediment layers. Large-scale extraction of natural gas hydrate may trigger submarine landslides; therefore, an appropriate constitutive model is necessary for the safe exploitation of natural gas hydrates. In this paper, a bounding surface model of gas-hydrate-bearing sediments (GHBSs) is developed based on the modified Cam-clay model. The size of the bounding surface is related to hydrate saturation by introducing an additional hardening parameter. It is assumed that the additional hardening parameter is related to the hydrate saturation level and plastic volumetric strain. The method for determining the model parameters is given. The model is used to simulate the triaxial compression drainage test of GHBS under different test conditions. It is demonstrated that the model can adequately capture the main deformation characteristics of GHBS. The proposed model is implemented into a finite-element method software program, and finite-element modelling of the plane strain test is carried out. The comparison of results shows the validity of the model.