Triaxial tests on anisotropic consolidated methane hydrate-bearing clayey-silty sediments of the South China Sea

Abstract

Comprehensive mechanical investigations must be undertaken for hydrate-bearing clayey-silty sediment to ensure their long-term suitability and safety. Affected by the earth pressure and stress history, the stress state of hydrate-bearing clayey-silty sediment typically presents anisotropic. In this study, 12 anisotropic consolidated shearing tests were conducted, the results show that stress-strain curves exhibit a strain-hardening trend and volumetric contraction for isotropic consolidated hydrate-bearing sediments at the typical saturation (∼30%) and pore porosity (∼45%). The internal friction angle is proportional to the consolidation stress ratio, while the cohesion is inversely proportional to consolidation stress ratio. The increasing consolidation stress ratio and effective confining pressure lead to an increasing failure strength, mainly due to the higher stresses causing a tighter alignment of soil particles, limiting the free motion of the particles and the extension of cracks. The presence of the initial axial stress leads to an interparticle locking in the soil skeleton.