The development of the stresses and displacements in the seabed caused by the dissociation of gas hydrate were numerically simulated by using the software ABAQUS. The effects of the dissociation size and the sustaining strength of the gas hydrate sediment after dissociation on the responses of the sediment were mainly investigated. It is shown that the deformation and the stresses in the seabed increased with the expansion of the gas hydrate dissociation size. The sediment will subsequently lose the stability or even slide when the strength of the gas hydrate sediment decreases and the gas hydrate dissociation size increases to some extent.
Natural gas hydrate is a crystalline solid usually occurring in deep ocean and permafrost. It has been estimated being of two times as much as the carbon resources on the Earth and thought as a kind of new potential energy in the 21st century. The gas hydrate dissociation in the seabed, which is usually due to the increase of the temperature or the decrease of the pressure, can cause the seabed settle or even slide. Therefore, it is very important to investigate the responses of the dissociation of gas hydrate on the stability of seabed. Some researchers thought that the Storegga slide in Norway (Locat et al, 2002; Hovland et al, 2001), Cape Fear slide in east coast of America and the landslide in the continental shelf of West Africa (Kayer et al, 1991; Sultan et al, 2004) and some other slides (Gilles et al, 1999) were all caused by gas hydrate dissociation. However, previous researches on this kind of landslides were almost based on geophysics and geochemistry investigation data (Paull et al, 2003; Bunz et al, 2003; Rao et al, 2002), but less researches were on the mechanism.
