Deviatoric Creep Effect of Unsaturated Soil during Shearing under Different Suctions and Stress Histories

In this research, creep behavior during shearing (deviatoric creep) was studied through a series of constant water content triaxial tests for unsaturated soil under different stress histories. The test samples were first compressed to a net confining pressure of 400 kPa and three different overconsolidation ratios (OCRs = 1, 2, 4) were obtained by unloading the confining pressure from 400 to 200 and 100 kPa, respectively. The samples were then dried with different sections (0, 150, 300, and 500 kPa) by the axis-translation technique. After that, the unsaturated samples were sheared until the deviatoric stress ratio reached around 1.2, and the axial stress was maintained during shearing until failure or reaching 200 h. The responses of samples, including the time, volumetric strain, axial strain, degree of saturation, and suction, were monitored during the triaxial testing. The test results are presented and thoroughly discussed in this paper, including the relationships between the deviatoric creep effect and stress history effect under different suctions.