Strength behaviors of hydrate-bearing clayey-silty sediments with multiple factors

Abstract

As a kind of new clean energy, natural gas hydrate has attracted the attention of the world. A full understanding of the physical properties that determine the strength behaviors of hydrate-bearing sediments (HBS) is hence required prior to the safe and efficient exploitation of the hydrates. Due to the lack of research work on fine-grained HBS, clay collected from the South China Sea and quartz sand were used to remold hydrate-bearing clayey-silty sediments (HBCSS). A series of consolidated-drained triaxial tests were carried out to determine the strength behaviors related to relationships between the physical properties of HBCSS. The results showed that higher saturation facilitates strain softening, while a higher confining pressure tends to result in strain hardening. The higher the clay content, the lower the failure strength and secant modulus E50 value. Clay can lubricate particles, hence an increase in clay content could lead to an increase in cohesion, but a slight decrease in the internal friction angle. The confining pressure and hydrate saturation were the main factors influencing the failure strength, while clay content had a limited influence on resistance to failure. The factors influencing the secant modulus E50 value could be arranged in a descending order of significance, namely hydrate saturation > clay content > confining pressure.