2006 Volume 62 Issue 2 Pages 546-561
Mudflow type failures of natural slope and artificial fill composed of volcanic sandy soil occurred during past earthquakes. In this study, the results of cyclic tri-axial tests of unsaturated volcanic sandy soil measuring pore air pressure, pore water pressure and volume change of soil are reported. Tests are conducted for specimens with various initial suctions and the same dry density under undrained condition both for pore air and pore water. Loose volcanic sandy soil specimen subjected to cyclic shear lost effective stress even if the degree of saturation was about 75%. Based on the test results, the liquefaction mechanism of unsaturated soil was discussed. It was concluded that the fluidization potential depended on the degree of saturation (initial water retention condition) and volume compressibility of the soil.
