Thermodynamics-based bounding surface model for gas hydrate-bearing sediments and its numerical implementation

Abstract

In-depth research on the mechanical properties and constitutive models of gas hydrate-bearing sediments (GHBSs) is fundamental for achieving efficient hydrate exploration and geological disaster prevention. In the current study, a bounding surface model for GHBSs is developed based on the principle of thermodynamics. By choosing an appropriate dissipation function and free energy function, a yield surface function containing three shape parameters can be obtained. Considering the filling and bonding effects of hydrates, and introducing the hydrate strength evolution parameter, a thermodynamics-based bounding surface model for GHBSs is established using a non-associated flow rule. Then, the explicit substeping scheme with error control is implemented to develop a UMAT subroutine for the proposed model and integrated into the ABAQUS. Compared with the drained monotonic triaxial shear data indicates that the proposed model can adequately capture the shear behaviors of sandy, silty sandy, and clay-silty GHBSs under different stress levels and saturations. In addition, the model demonstrates good applicability and feasibility in undrained cyclic triaxial shear tests and boundary value problem analysis.