Influence of the Constant Deviator Stress on Deformation Characteristics of Saturated Sand Under Cyclic Spherical Stress

The recognition of stress–strain characteristics of soil under stress path of cyclic spherical stress and constant deviator stress is not sufficient, which can enhance understanding of structural behavior during cyclic variation of pore water pressure. Triaxial tests with cyclic spherical stress were carried out on Fujian sand. The influence of consolidation deviator stress on the stress–strain relationships was discussed. The results showed that the cyclic loading of spherical stress led to significant volumetric strain and shear strain in soil. The volumetric strain increased/decreased with the increase/decrease in spherical stress in each cyclic process. The relationships between volumetric strain and the logarithm of spherical stress could be approximately described as linear. The shear strain progressively increased with the increase in spherical stress in each cycle, but the growth was all less than 0.1%, and could be neglected. When spherical stress decreased, the shear strain featured diverse trend under different deviator stress, but the variation was on the same line with the increase in stress ratio, so the stress ratio was the key factor affecting the shear strain. The influence of consolidation deviator stress on the volumetric strain was little during the initial loading stage and became obvious during the subsequent reloading and unloading stage. The accumulative volumetric strain under different deviator stress was almost uniform. The consolidation deviator stress had great influence on the accumulative rate of shear strain, and the conspicuous initial deviator stress usually determined the development direction of accumulative shear strain.