According to the fact of the undrained shear strength decreasing during field vane test, applying the cylindrical expansion theory, it is assumed that saturated soft clay satisfies Tresca yield criterion, and then the disturbance degree function is given on the basis of the sensibility of saturated soft clay, and the function D is logarithm function of the plastic radius. Considering the undrained shear strength su is the function of the disturbance degree, the elastoplastic...
