Review of N Models in Simulating Mechanical Behavior of Clays

Abstract

In traditional clay modeling, the form of the yield surface was usually proposed by curve fitting the yield points of the particular clay studied, thus the application of the resulting model could be limited to particular clays. Different from that, through a careful examination of a database of yield surfaces for natural clays, the form of work dissipation based yield surface of Dafalias was adopted. A surface configuration parameter, N, was introduced to the yield surface by emphasizing on the relationship between the shear strength and the shape of yield surfaces for clays. This yield configuration parameter in fact represents a measure of the shear strength over the anisotropic line. Its numerical value can be different from the surface configuration parameter of the plastic potential, M, which also represents a frictional constant associated with the critical state. The resulting models developed with the yield surface configuration parameter, N, would be simply called N models for convenience. Simulations of mechanical behavior of different types of clays under various shearing modes were briefly reviewed here. The review may indicate that the N models have potential wide range of applications to different type of clays, and have the capacity to accurately capture the shear strengths.