Geotechnical characterization of index and deformation properties of Stockholm clays

Abstract

<abstract> <p>This paper describes the geotechnical characteristics of index and deformation properties of Stockholm clays. These clays exhibit large variations both geographically and with depth. The clays range from highly organic clays with high plasticity to silty clays with low plasticity. First, the geological conditions of the clays are outlined to qualitatively explain the typical soil stratigraphy encountered in the Stockholm area. Second, two large generic databases are presented, containing 3,500 and 1,600 data points, respectively. The data originates from routine testing and constant rate of strain oedometer tests conducted in commercial projects. The data is analyzed and compared with results from high quality block sampling. It is seen that a common feature of the clays are low undrained shear strengths, and consequently low yield stresses and oedometer moduli. Further, several deformation properties such as preconsolidation pressure and several oedometer moduli is shown to depend on the soils natural water content and its plasticity. Differences in sample quality is shown to highly affect some properties, highlighting the importance of quality sampling and handling of samples. Criteria for sample quality for this type of clay is proposed based on the oedometer moduli before and after the preconsolidation pressure. The paper can hopefully work as a useful reference to engineers working on similar soils worldwide.</p> </abstract>

Factors affecting the oedometric modulus of till soil

“…The summarized study findings confirm that the interaction between the finest fraction (clay) content and the amount of water exerts the greatest control over the engineering behaviour of till soils (Ural 2018;Wang et al 2021;Hov, Gaharia 2023;Shaochun et al 2023).…”

“…The understanding of the existing correlation between these soil properties is essential for working out practical application solutions. As highlighted by numerous researchers, an increase in water content leads to a decrease in soil strength, deformation modulus value, coefficient of consolidation (C v ), and the angle of internal friction (φ) (Malizia, Shakoor 2018;Habtemariam et al 2022;Hov, Gaharia 2023). Some research indicates that compressive strength of soil increases with clay plasticity (Malizia, Shakoor 2018).…”

“…The performed analysis of the derived model's reliability (Table 1) shows that the content of natural water and that of fine fraction (clay) as well as soil cone resistance are the most reliable indicators for the correlation existing between the determined and the estimated oedometer deformation moduli. According to numerous researchers, the content of natural water content and that of fine fraction (clay) in soil are the main factors determining its deformation properties (Wang et al 2021;Hov, Gaharia 2023).…”