The Original Cam Clay Model

Let the compressive strain be positive, then the increment of the volumetric strain is given as 

6 Classical Theory of Consolidation for Saturated Porous Media 

If the clay is in a normally consolidated state, referring to Fig. 6.4a, an elastic component de and plastic component de of an increment of the void ratio de = de - -de is given by 

Here M is the slope of the critical state line CSL shown in Fig. 6.2d, and we define D as 

If we have a general stress state as shown in Fig. 6.4b, the results (6.69)-(6.74) are satisfied. In addition we can introduce the stress state on the normally consolidated line p = p y,q = 0) under the same condition of void ratio as 

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The original Cam clay model employs isotropic hardening with strain hardening such as... 

Finally we obtain the following yield function, which is referred to as the original Cam clay model. 

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