Static shear behaviors of methane hydrate and ice are discussed in this paper. Based on the triaxial compression test results under low temperature and high pressure, their static shear behaviors are compared. As the results, temperature is very sensitive condition to control static shear behavior of methane hydrate. Compressive strength of methane hydrate or ice increases as decreasing temperature or increasing pressure. Compressive strength of methane hydrate is greater than that of ice. In case which the test conditions are very close to the stability boundary of methane hydrate, compressive strength of the hydrate is almost equal to that of ice. Initial shear modulus of ice is greater than that of methane hydrate because of bedding error.
Methane hydrate is one of solid hydrated forms of natural gas. In this hydrated form, methane molecules are taken in a cage of water molecules. In recent years, it is considered as an encouraging new energy resource to replace oil and natural gas, because of such huge amount of reserves as estimated that it is sufficient to last over 100 years based on present levels of natural gas consumption (Matsumoto et al., 1993). Especially, it would be found at the edge of tectonic plates around Japan islands under the ocean floors in the Pacific Ocean. Methane hydrate is stable at low temperature and high pressure. The Japanese methane hydrate exploitation program has been established and first methane hydrate extraction trials in Japan were carried out at the Nankai Trough off the Omaezaki Cape in 1999. However, the reckless mining development might cause serious disasters such as sliding or mass movement of unstable seabed. To prevent such disasters due to the methane hydrate mining development, it is necessary to understand its mechanical properties from the geotechnical viewpoint.