Statistical damage constitutive model based on self‐consistent Eshelby method for natural gas hydrate sediments

• Published in: Energy science & engineering 2021-11, Vol.9 (11), p.2079-2098
• Main Authors: Wang, Feifei, Wang, Zizhen, Zhang, Di, Wang, Zhenqing
• Format: Article
• Language: English
• Subjects: Composite materials; constitutive model; Constitutive models; Damage; damage model; Energy sources; Eshelby's inclusion theory; Gas hydrates; Gases; Homogenization; Marine sediments; Mathematical models; Mechanical properties; Micromechanics; Natural gas; Natural gas hydrate; Permafrost; Phase transitions; Plastic deformation; Sand & gravel; Sediments; self‐consistent method; Shear strength; Shear tests; Statistical methods; Stiffness; Trace elements; Weibull statistical distribution
• ISSN: 2050-0505; 2050-0505
• DOI: 10.1002/ese3.968

Natural gas hydrate (NGH) is widely distributed in marine sediments and continental permafrost, which is a promising energy resource. The sustainable and safe exploration and production of NGH requires fully understanding of its mechanical behaviors, which is still a challenge to our community. In this paper, a statistical damage constitutive model named SC‐SDCM is developed for NGH sediments. The NGH sediments are regarded as two phases: the matrix phase of solid mineral grains, pore fluid, and gas, and the inclusion phase of hydrate crystal. The effective elastic parameters of such two‐phase composite are estimated by self‐consistent method (SC) according to the equivalent inclusion principle of micromechanics. The mesoscopic element strength of the NGH sediments is described by the Weibull statistical distribution and the damage theory of composite materials. And then combined with the Drucker‐Prager failure criterion of microelement, the damage constitutive model of NGH sediments is established. The new SC‐SDCM is tested to be reliable and robust by triaxial experimental observations on artificial cores and naturally occurring samples under different confining pressures and hydrate saturations. The SC‐SDCM could properly describe the stiffness, peak strength, and strain softening properties of the NGH sediments. Moreover, the predictions of SC‐SDCM are closest to the experiment observations compared to several published constitutive models, especially for the near‐ and after‐damage stages with relatively high hydrate saturation. Natural gas hydrate is an important and promising energy resource, and it is of great significance to well understand the mechanical properties of NGH sediments for the safe and sustainable exploitation and prevent geological disasters. In this paper, a novel statistical damage constitutive model based on self‐consistent Eshelby method through theory of micromechanics is established and suit for predicting the mechanical properties of natural gas hydrate sediments accurately and conveniently.