Rate Effects in Clay

Abstract: Although there are many observations of rate dependent properties of clays in laboratory element tests there are no credible model formulations that consistently describe strain rate effects in shearing or creep and relaxation in compression. The current research aims to develop and validate an elastic-viscoplastic framework for clays that can extend prior elastoplastic models developed at MIT. The research makes extensive use of unique experimental data on rate dependent undrained shear behavior and effects of prior stress history. The goal is to develop a model that will resolve an enduring controversy (within the geotechnical community) regarding the coupling of consolidation and creep (secondary compression), and hence enable more reliable predictions of long-term ground movements for structures founded on soft clay.