This work focuses on characterising the volume changes in the blue marls of the Guadalquivir Basin through the application of innovative experimental tools and numerical formulations that account for the influence of suction. Such aspects have necessitated new studies in geotechnical projects related to volumetric changes, loss of strength, and instability of partially saturated soils.

Context and Motivation

In Andalusia, the lack of an extensive and in-depth study on the influence of suction on the deformability of overconsolidated clays, such as the Guadalquivir blue marls, has led to significant geotechnical disasters. These disasters are often associated with frequent risks of landslides, slope failures, tunnel collapses, severe infrastructure safety issues, and environmental impacts. Notable incidents include:

• The El Carambolo landslide, which threatened the beautiful Sevilla botanical garden (El Arboreto).
• The Almodóvar del Río landslide (Córdoba), which affected the Madrid-Seville high-speed train line.
• The Aznalcóllar landslide, which caused a tailings dam failure, resulting in a natural disaster due to the release of mining waste.
• The Las Cruces mine landslide.

Research Approach

The physical and mechanical characteristics of the blue marls were studied through various identification tests (e.g., granulometric analysis, Atterberg limits, densities), mineralogical and chemical characterisation tests (e.g., X-ray diffraction, scanning electron microscopy, mass spectrometry, mercury porosimetry), and specific techniques for controlling and imposing suction, such as filter paper, psychrometers, and vapour equilibrium with saline solutions, to obtain the unconfined retention curve of the marls.

Conclusion

This research provides critical insights into the volumetric behaviour of the Guadalquivir blue marls, addressing a gap in geotechnical studies in Andalusia. By employing advanced experimental and numerical approaches, the study enhances the understanding of soil behaviour under partially saturated conditions, thereby contributing to safer and more reliable geotechnical engineering practices in regions with similar soil profiles.