Simplified 1D Empirical Model for Volumetric Behavior of High-Carbonate Clay

The Guadalquivir blue marl is a high plasticity overconsolidated carbonate clay. This soil presents an elevated fragility and high susceptibility to moisture changes. These characteristics have caused many geotechnical accidents, such as the Aznalcollar dam failure, in Seville (Spain). A comprehensive test campaign has been conducted to determine the physical and chemical properties of the blue marl. Analysis by scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) allowed characterising its internal structure, revealing clear differences between the macro and the microstructure. A novel model for predicting the volumetric deformation (under oedometric conditions) of the Guadalquivir blue marl with suction and vertical pressure changes has been proposed. The model, based on data from shrink-swell tests, provides an acceptable estimation of the volumetric behaviour of the soil with a relatively simple set of parameters. The results were experimentally verified by suction-controlled oedometer tests and showed an acceptable agreement with the data measured. It has been specified when swelling. shrinkage or collapse occur.