Abstract: In order to investigate the consolidation and permeability characteristics of gassy submarine soft soil, a new device that could perform the consolidation and the permeability tests was developed. In the new device, the automatic separation and measurement of water and gas drained from the gassy soil sample and the desired water and gas tight during the test were achieved and the friction in the sample ring and piston was effectively reduced. The test results show that the compression index of gassy soft soil has a linear relationship with the gas content in the soil sample; the permeability coefficient is controlled by both the void ratio and gas content; gas content only affects the value of permeability coefficient but has no significant effect on the evolution law of the permeability coefficient; with the increase of the initial gas content, the growth of gassy soft soil consolidation speed slows down, or even decreases.

Key words: gassy soft soil, water-gas separation, consolidation characteristics, permeability coefficient