Gas hydrate dissociation may lead to soil stratum instability such as marine landslides in hydrate-bearing sediments. In this paper, centrifugal tests were conducted to investigate the soil responses and stratum instability of a 14 degrees slope during hydrate dissociation under centrifugal accelerations of 50g and 100g, different boundary conditions and heating modes. New phenomena such as sliding of the over layer, layered fractures between the hydrate layer and the over layer, and fractures in the over layer were observed. The fluid pressures, horizontal displacements and vertical displacements of the soils were measured and compared under different conditions. The observed mechanisms and decoupled formulations considering heat transfer, fluid seepage, soil deformation and critical soil failure were presented and discussed. The formation of layered fractures during hydrate dissociation is regarded as an important factor leading to the instability of the slope.

This study is funded by China Geological Survey (No. GZH201100311), National Natural Science Foundation of China (Nos. 51239010, 11102209), and CNPC-CAS cooperation project (No. 2015A-4813).