To improve the understanding of the mechanical behavior of the gas-hydrate bearing sediments

a series of triaxial compression texts was performed on gas saturated CO2-hydrate-bearing sand. Samples were prepared using the excess gas method

in a modified high-pressure low-temperature triaxial apparatus. The hydrate saturation could be determined readily according to the gas assumption. The repeatability of sample making was analyzed in terms of the hydrate saturation. It was found that samples with high hydrate saturation could be formed from samples with high initial water saturation

however

the repeatability of making samples

which was affected by pore blocking effect

was low. It was shown that the repeatability of making samples with hydrate saturation lower than 40% using the excess gas method was relatively good. The triaxial test results show that the mechanical behavior of hydrate-bearing sand samples depends largely upon the hydrate saturation and the applied net confining pressure. The strength

stiffness

ductility and compressibility of hydrate bearing specimens increase with the effective confining pressure; as hydrate saturation increases

the strength and stiffness of specimens increase

while the ductility and compressibility decrease. In addition

the larger the hydrate saturation

the larger the apparent cohesion

whereas the friction angle remains practically unchanged.