Mechanical properties of saturated remolded loess under different stress paths

Abstract

The mechanical properties of soil often vary with stress state and stress paths. In order to investigate the mechanical properties of saturated soil under vertical loading and constant shear stress path, saturated remolded loess samples are prepared. Through consolidated undrained (CU) triaxial tests and constant shear stress drained (CSD) triaxial tests, the corresponding stress-strain curves, pore water pressure curves and stress path curves are measured. The results show that the saturated remolded loess has obviously different deformation characteristics under the two paths. In CU tests, the stress-strain curves are softening weakly. The pore water pressure rises rapidly and tends to be stable gradually. In CSD tests, the deviator stress is a constant and the pore water pressure is applied. The deformation of samples is small for a long time at the beginning. When the pore water pressure increases to 60%−75% of the confining pressure, the samples are destroyed rapidly. Because there is no peak value of deviator stress in CSD path, the equivalent peak failure line is defined according to the axial strain-mean effective stress curves. By comparison, it is found that the effective peak strength indexes of the saturated remolded loess are significantly different under the two paths. However, the effective residual strength indexes are similar, indicating that the effective residual strength indexes are the internal attribute of the remolded loess and are not affected by the stress path. This study can provide reference for selecting the correct stress path test in practical engineering.

Keywords

• remolded loess
• stress path
• deformation
• strength
• pore water pressure