Some Design Considerations for Embankments on Rate Sensitive Soils

Both the short-term and long-term behavior of reinforced embankments constructed on rate sensitive foundation soils is investigated. Factors such as the rate sensitive properties of the foundation soil, reinforcement stiffness, construction rates, and different foundation soil profiles are considered. The strain rate at which the foundation soils deform during and after embankment construction is examined. For embankments on these soils the analysis indicates that the critical stage with respect to stability occurs during a period of creep and stress relaxation in the foundation soils after construction. The strain rate corresponding to this critical stage controls the operational shear strength of rate sensitive foundation soils and this strain rate falls into a relatively small range of values for the wide range of conditions examined. A technique that allows a conventional undrained limit equilibrium analysis to be modified to allow the design of reinforced embankments over rate sensitive foundation soils is proposed based on the critical stage concept.