yielding behavior of natural clay considering stress history subjected to k 0-consolidation

This study investigated the yielding behavior of natural lianyungang clay by considering the stress history. a series of drained triaxial tests with different stress paths were conducted on the undisturbed lianyungang clay under k0-consolidation. a modified yield function was developed for the natural soft clay, for which the parameter ηk0 was replaced by ηk in the equation for the yield surface from the existing model. the modified equation can describe the effects of stress history and anisotropy on the natural soft clay, and capture the degradation of soil structure. results showed that the yield surface would rotate clockwise with increasing pre-consolidation stress. as the pre-consolidation stress increases, the slope of the symmetric axis decreases from ηk to close to zero. an exponential equation can be well fitted between the slope of the symmetric axis of the yield surface and the pre-consolidation stress (or over-consolidation ratio, ocr). the effects of stress history and loss of the soil structure are captured well by the modified equation for the yield surface. angles (θ) between direction of plastic flow under different stress paths and the normal direction of yield surface vary from − 30° to 36°, suggesting the direction of plastic flow in the post-yield state can be described by the associated flow rule.