Effects of Different Mining Methods on the Strength Behavior of Gas Hydrate-Bearing Sediments

Abstract

The mining of methane hydrate from permafrost can cause the permafrost strength decreasing, softening and straining. It will be helpful to understand effects of different mining methods on the mechanical properties of hydrate-bearing sediments. In this paper, two kinds of hydrate dissociation methods (depressurization and heating) were conducted in triaxial pressure chamber. The mechanical properties of methane hydrate-bearing sediments after dissociation were measured by a low-temperature and high-pressure triaxial compression apparatus under exhaust and non-exhaust shear test. In addition, triaxial shear test of the CO2 and CH4 hydrate-bearing sediments prior to dissociation were also carried out in the identical conditions. The experimental results under the two kinds of dissociation methods showed that the strength of the methane hydrate-bearing sediments after dissociation is less than that before. The shear strength under the consolidated exhaust and consolidated non-exhaust shear tests was also quite different.