Behavior of sands in constant deviatoric stress loading

Many instances of flow-type slope failures are believed to be caused by changes in soil stresses resulting from rises in pore water pressure; among them are submarine flowslides and mining waste dump failures. In a soil mass, a rise in pore water pressure leads to a decrease in mean effective stresses, while the vertical gravity load remains unchanged. Similar loading may be applied to a soil sample in the triaxial apparatus by keeping the deviatoric stress constant, while the confining pressure is decreased. Previous research has shown that under such loading, loose sands initially dilate slightly, and then start to contract substantially as failure is approached. These contractions can lead to the increase in pore pressure and, consequently, failure of the soil mass. The current study shows that these volume contractions are affected by factors such as void ratio, confining pressure, level of deviatoric stress, and anisotropic consolidation.