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

Abstract

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 was conducted to determine the physical and chemical properties of the blue marl. Analysis by scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) allowed characterization of its internal structure, revealing clear differences between the macro- and microstructure. A novel one-dimensional (1D) model for predicting the volumetric deformation (under oedometric conditions) of the Guadalquivir blue marl with suction and vertical pressure changes was proposed. The model, based on data from shrink–swell tests, provided an acceptable estimation of the volumetric behavior 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. The proposed model is valid for ranges of swelling, shrinkage or collapse.