Soil structure and anisotropy were generated during the depositional process for natural sedimentary soils

which made them different form that of the remolded soils. Since natural soils may generally undergo different stress paths during external loads in the engineering practice; it is necessary to carry out stress path tests on natural soils both considering the effects of soil structure and anisotropy. Analysis of mechanical behavior under different stress path tests can be the basis for set up reasonable constitutive model for natural soils. In this study

different K0 consolidation drained stress path triaxial tests were performed by GDS triaxial apparatus on undisturbed Zhangjiagang silty clays

which were taken by large diameter PVC samplers from depths of 2.5m underground. Test results show that stress paths exert significant influence on volumetric and shear deformation. Global stress and deviator stress have cross effects on the volumetric strain and shear strain. Obvious yielding behavior can be observed in stress-strain relations

whatever the stress paths are controlled by volume or shear deformation. Yielding curve obtained by connecting the yield points under different stress paths shows an incline elliptical shape

which agrees better with the yield curve in the constitutive model proposed by Wheeler et al. than that of the model presented by Nakano et al..