Abstract
A brief explanation of the mathematical representation of state surface and swelling wall is given based on the stress-void ratio relations of clays. The changes of the mechanical state of normally consolidated and overconsolidated clays stressed under various conditions are derived. Combining the concepts of state surface and normality, general incremental stress-plastic strain relations for clays are given. The stress-strain relations for normally consolidated and overconsolidated clays under various conditions are also discussed. The theory can only be applied to the prediction of strains where the void ratio is a unique function of the imposed stresses.
