Strength estimation for hydrate-bearing sediments based on triaxial shearing tests

Abstract

Evaluating deformation characteristics and predicting strength parameters of hydrate-bearing sediments (HBS) are indispensable for natural gas hydrate exploration and development. A series of triaxial shearing tests were conducted in this paper to analyze the mechanical behaviors and failure mechanisms of hydrate-bearing sediments. The failure strength is discussed comprehensively based on the Mohr-Coulomb criterion, the Drucker-Prager criterion, and the Lade-Duncan criterion. Failure mechanisms of the specimens during shearing are discussed at the micro-level. The results indicate that specimens with relatively high hydrate saturation exhibit strain-softening brittle failure mode, whereas those with relatively low hydrate saturation exhibit obvious strain-hardening ductile failure mode. The cohesion of HBS is enhanced from 0.42 MPa to 1.0 2 MPa, and the friction angle increases from 26.4° to 34.2° with hydrate saturation rising. Additionally, the modified criteria based on the Drucker-Prager criterion can predict the strength with the highest accuracy. The results provide a theoretical and experimental reference for developing the natural gas hydrate reservoirs efficiently.