Effect of confining pressure on mechanical behavior of methane hydrate-bearing sediments

Abstract

Synthesized gas hydrate in lab was mixed with kaoline to form core samples, so as to simulate the hydrate-bearing sedimentary layers in the seabed. Under conditions of different confining pressure, triaxial compressive tests were conducted on hydrate-bearing sediments with different volume content of kaoline. The results show that: (1) The failure strength of gas hydrate-bearing sediments increases with the confining pressure at a low-pressure stage. The strength tends to decline gently with further increases of confining pressure. (2) The modulus of elasticity E0 keeps unchanged under various confining pressures. But the secant modulus E50 presents a great dependency on the confining pressure. Secant modulus increases to the peak and then decreases with the increase of confining pressure; (3) The internal friction angles of gas hydrate-bearing sediments are not sensitive to the volume ratio of kaoline, but its cohesion depends on the volume ratio of kaoline. The sediment strength increases with the increase of kaoline content. Key words: natural gas hydrate, mechanical property, seabed sediment, triaxial testing, safe extraction