The bank slope soils are periodically influenced by the fluctuation of reservoir level

and its stress process can be described as multi-cyclic loading-unloading process of the effective stress in the pre-consolidation pressure range. The triaxial test of soil stress path is used to simulate the cyclic loading-unloading of soil pore water pressure

and the deformation and development laws of soil are predicted by extending the unified hardening model and modifying the loading-unloading criteria. The results show that during the cyclic loading-unloading process

the volume deformation of the soil is periodically elastic

and the shear strain is in a spiral upward trend and its increment gradually decreases with the number of cycles. During the unloading and confining pressure yielding stage

the soil deformation shows a dilatancy feature of volume expansion and a brittle trend of shear strain increase. The measured pore pressure drops dramatically and the peak intensity point occours when the shear deformation is at about 6%. The relationship between the compression curve coefficient and the number of loading-unloading is established

and the loading-unloading rules of the overconsolidated soil are modified. The extended unified hardening model can predict the deformation characteristics of the bank saturated soil under the special stress paths.