Creep behaviors of methane hydrate coexisting with ice

• Creep behaviors of methane hydrate coexisting with ice were obtained.
• External load, confining pressure, and temperature strongly affect creep behaviors.
• Axial strain and creep strain rate increase with the increase of external load.
• High confining pressure and low temperature enhance the resistance of deformation.

A series of creep tests were carried out in order to clarify the creep behaviors of methane hydrate coexisting with ice, which may exist in the ice-bearing permafrost. Measurements on synthetic methane hydrate-ice specimens indicate that (1) higher external load will increase the initial strain and the axial strain during the whole creep test. And the creep strain rate will increase with the increase of external load; (2) the initial strain, axial strains and creep strain rate of the specimens under certain external load increase with the decrease of confining pressure; (3) temperature drop leads to the decrease of initial strain and axial strains of the specimens under certain external load. And the creep strain rate firstly increases and then decreases with the increase of temperature, due to the refreezing of dissociated water from methane hydrate; (4) the specimens run to the secondary creep stage earlier when they endure lower external load, higher confining pressure and lower temperature; (5) the specimens under higher confining pressure and lower temperature show higher failure strength.