Abstract: Two Cam-clay models, including the original and the modified, were established on phenomenon of the conventional triaxial tests on normal and lightly over consolidated soils. That is to say the initial stress state of the triaxial sample is isotropic other than anisotropic. Application of the two models on the intact soil in K0 consolidation inevitably leads to systematic errors that could not be ignored. Based on the relationship between K0 line and isoclinic line for the intact soil, the Cam-clay model and modified Cam-clay model for the intact soil were constructed by circumvolving the two models along a special line. The improved model can reflect the structure and anisotropy of intact soil due to K0 line taken as the axis rather than the isoclinic line in principal stress space. Experimental data verify that, the improved model can describe the yield and strength characters of the intact soil more reasonably than two Cam-clay models.

Key words: structural, Cam-clay model, isoclinic, initial stress line, plane loading