Analyses of stress strain behavior and constitutive model of artificial methane hydrate

In this paper, a low-temperature high-pressure triaxial test system including pressure crystal device (sample preparation system) was developed, in which the conditions of hydrate stabilized can be maintained. To determine the stress strain behavior of methane hydrate, the triaxial shear tests were performed under the condition of strain rates of 1.5%/min, temperatures θ = − 5, − 10, and − 20 °C and confining pressures P = 2.5, 5 and 10 MPa. The preliminary results show that the stress strain curves can be divided into two stages: the rapid structural damage stage and the complete structural damage stage (or the yield stage). Based on the experimental and analysis results of stress strain behavior of triaxial tests, this paper proposes a modified nonlinear elastic Duncan–Chang constitutive model suitable for artificial methane hydrate. The modified model takes into account the effect of temperature and confining pressure as well as hydrate structure on the stress strain behavior. By comparing experimental with simulation results, the validity of model had been evaluated.

Research highlights
► In this paper a triaxial testing equipment with low temperature and high pressure was developed to determine and analyze the mechanical behavior of artificial methane hydrate in various conditions.
► The constitutive model suitable for artificial methane hydrate was established on the basis of nonlinear elastic Duncan–Chang model.