Triaxial Shearing Characteristics of Hydrate-Bearing Silty-Clayey Sediments under Deviatoric Consolidation

Abstract

The stress differences between the overburden weight and horizontal soil pressure result in the reservoir of the South China Sea being subjected to various stress states. Understanding the mechanical responses of hydrate-bearing silty-clay sediments under varying consolidation states, particularly under typical deviatoric consolidation conditions, is essential for the sustainable and safe extraction of hydrates. Hydrate-bearing silty-clayey sediments were prepared under varying consolidation states using isotropic or deviatoric consolidation methods, and their mechanical behaviors were analyzed through triaxial shearing tests. The results indicate that hydrate saturation affects the inflection point of strain hardening curves in deviatoric consolidation sediments. The sediment failure strength demonstrates a positive linear correlation with hydrate saturation, consolidation stress ratio, and effective confining pressure. Sediments subjected to deviatoric consolidation exhibit stronger cohesion; however, the deviatoric consolidation method does not alter the effect of hydrate saturation on sediment cohesion and the internal friction angle. The consolidation stress ratio and effective confining pressure influence the volumetric deformation of sediments through competing effects of compaction-induced reduction in residual compressibility and particle breakage-induced filling of pores by smaller particles. The effect of hydrate saturation on sediment volumetric strain is jointly influenced by variations in pore space, shearing dilation trend, and effective stress. The strength and deformation characteristics of hydrate-bearing silty-clayey sediments under deviatoric consolidation conditions are investigated in this study, with the objective of providing theoretical support for hydrate extraction in the South China Sea.