OS1B-7:DISCUSSION ON THE MECHANICAL BEHAVIOR OF GAS HYDRATE SEDIMENTS BASED ON THE DRILLING CORES FROM THE SOUTH CHINA SEA BY TRI-AXIAL COMPRESSIVE TESTS

    China’s researchers confirmed the Natural Gas Hydrate in the Tibetan Plateau and the South China Sea. It is important to research the mechanical behavior of hydrate bearing sediment in-situ conditions. This paper describes the recent tri-axial compressive tests on the Φ50 mm×100 mm synthetic natural gas hydrate specimens under sediment conditions. The mainly sand specimens of marine gas hydrate were discovered in the sediment’s cores of the South China Sea hydrate drilling program in 2007. The testing apparatus can apply the maximum capabilities of 250 kN for axial loading with accuracy of 0.1%/min strain-rate, 30 MPa for confining pressure and 20 MPa back pressure. The temperature inside the chamber can be controlled at the range from 243 K to 323 K with an accuracy of 0.5 K by circulating 50% ethylene alcohol solution from the refrigerator. The data of displacements, load, confining pressure, back pressure and temperature were acquired and recorded by the computer system at every 10 seconds during the test. The particle size distribution, stress and strain relationship, tri-axial compressive strength, elastic modulus, Poisson’s ratio and unloading processing rate would be discussed. The results of testing show the mechanical behavior in different gas hydrate saturation with the certain temperature and confining pressure and certain saturation with different temperature and confining pressure. Meanwhile, this test tried to focus on how much mechanical behavior changes by the different rate of gas hydrate dissolve.