Modified Cam-Clay model incorporating unified nonlinear strength criterion

A unified nonlinear strength criterion (i.e UNS criterion) is proposed, for the sake of versatility, to capture the complex strength behaviors of frictional materials in geotechnical field. It covers wide ranges on the meridian and octahedral planes to describe nonlinear strength behaviors of soils. The Modified Cam-Clay model, incorporating the unified nonlinear strength criterion, is employed as an example to derive working mathematical equations and to illustrate yielding surfaces in three-dimensional stress space for improving the model’s predictive capability. The unified nonlinear strength criterion, demonstrated here, is capable of capturing the experimental results of different types of soils on the meridian and octahedral planes. In addition, the revised model, based on this unified nonlinear strength criterion, though very simple, is versatile to predict the true triaxial test results from literature when considering the influences of the intermediate principal stress on strength and deformation under complex stress conditions.