ABSTRACT:

Submarine slope failures have been considered to have strong spatial relations with the occurrence of gas hydrates. The slope stability analysis used the shear strength reduction technique with a Mohr-Coulomb failure criterion to calculate the factors of safety. When the hydrate was stabilized in the slope, the hydrate zone would inhibit the expansion of the plastic zone due to the high strength of hydrate sediment with a slight increase of the slope safety factor. As the hydrate decomposition radius reached 100 m, the plastic zone first appeared in the hydrate decomposition zone, then spread to the top of the slope. In the period of the hydrate decomposition, Fs was significantly reduced to less than 1, which indicated that large-scale submarine landslides were contributed by the hydrate decomposition. Furthermore, with the identical degree of the hydrate decomposition, the deeper the burial depth of the hydrate, the higher the safety factor of the slope. The slope angle remarkably impacted the slope safety factors. When the slope angle was larger than 20°, the slight hydrate decomposition could cause the submarine landslides as well.

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