The behavior of loose gassy sand

Methane gas, found in loose deltaic deposits, can contribute to the triggering of flow liquefaction of submarine slopes. The behavior of loose gassy sand is studied in the laboratory using monotonic consolidated undrained triaxial compression tests. Samples consisted of reconstituted Ottawa sand prepared to degrees of saturation ranging from 80 to 100%. Gas contents were determined using a time domain reflectometry miniprobe with a series of calibrations relating apparent dielectric constant to degree of saturation. The results indicate that loose gassy sands can strain soften and experience flow liquefaction. If the degree of saturation is lower than the "cut-off" value, for a specific void ratio, flow liquefaction will not occur.