A statistical damage constitutive model of hydrate-bearing sediments

Hydrate saturation and effective confining pressure can significantly influence the mechanical behaviour of hydrate-bearing sediments. In the case, that the effects of the hydrate type, grain size, and testing conditions are excluded, these two variables are the critical factors that determine their elastic modulus. Based on the relationship between equivalent elastic modulus and hydrate saturation, a power function is established for the damage variable, which takes into account the influence of effective confining pressure. Drucker-Prager failure criterion is adopted to describe the strength of a micro-element of hydrate-bearing sediments. By assuming that the variation of the micro-element strength follows Weibull's distribution, a statistical damage constitutive model of hydrate-bearing sediments is developed. By comparing the simulated results with the experimental data available in the literature, we show that the proposed model can describe the stress-strain behavior of the hydrate-bearing sediments very well under the triaxial shearing condition. The results can provide reference for numerical simulation of engineering properties of gas hydrate sediments.