A mesoelastic-plastic damage model for hydrate-bearing sediments with various hydrate-growth patterns

Abstract

A mesoelastic-plastic damage mechanical model (Gurson-DP) is proposed to simulate the progressive failure caused by damage accumulation in hydrate-bearing sediments (HBS) under engineering disturbances. HBS is regarded as a complex of the matrix phase, inclusion phase and void phase. A combination of the Reuss and Voigt bounds is used to predict the macroscopic modulus of HBS. First, a mesodamage mechanical model is established based on Weibull random failure theory and Gurson plastic damage theory. Next, the analytical biphasic Hill equation of the yield stress for dilatation-softening HBS and equations describing void growth and nucleation are proposed to study the behavior of the matrix phase and void phase. Finally, the accuracy and validity of the model are verified by triaxial compression tests. The results show that our proposed model can simulate the entire stress-strain process of HBS from plastic yielding to softening. The model can accurately characterize the mechanical behavior of HBS, such as dilatation softening and cementation failure, and reasonably reflects its mesoscopic failure mechanism under complex stress paths. This paper comprehensively studies the complex mechanical response of HBS and provides a theoretical basis and technical means for improving hydrate exploitation.