Ieva Lekstutytė, Donatas Urbaitis, Gintaras Žaržojus, Šarūnas Skuodis, Saulius Gadeikis

Factors affecting the oedometric modulus of till soil

Soil deformation moduli are affected by a number of factors including the intensity of applied load in drained or undrained conditions, stress-strain characteristics, confining pressure, stress history, and soil type. Determination of the deformation properties of glacial soils requires long-term research. As evidenced by a review of previous studies, Lithuanian glacial soils are still insufficiently explored. Our study focuses on the deformation properties of till soil, specifically, on the properties that have a significant impact on soil settlement or compressibility, and its calculations. The current study presents the oedometer deformation modulus determined and predicted under stress at 0.2 and 0.4 MPa levels, which are most often used in geotechnical design. These index values allowed identifying the major factors responsible for the variation in deformation behaviour of different groups of till soils. The most significant finding of this study was the absence of a direct correlation between the oedometer modulus (Eoed) and cone resistance (qc). Instead, based on the content of natural soil water (w), proportion of fine fraction (clay), and cone resistance (qc), we found that the most reliable correlation exists between the determined (EDoed) and estimated (EEoed) oedometer moduli.
It is important to note that regression models are applicable and reliable only within specific ranges of these factors. The valid limits for these models are: water content in the range of 7.7%–15.4%, clay fraction in the range of 4.0%–20.0%, and cone resistance in the range of 1 MPa–5 MPa.


Keywords Soil compressibility; Robertson soil behaviour index (SBT); Sand-clay mixture; cone resistance

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