Abstract: The unified equation of the undrained shear strengths isdeduced by combining K0K_0 K0 overconsolidated clay model, the function ofrotating angle, the critical state conditions of the clay and thetransformed stress tensors based on SMP criterion. The stress Lodeangle K0\theta K0 and the rotating angle K0\omega K0 under the triaxialcompression and extension condition, and under the plane strain compressioncondition are applied to develop the corresponding undrained shear strengthequations, respectively. The theoreticalresults for K0K_0 K0 overconsolidated clays are in good agreement with theexperimental data.