Unsaturated Strength of a Compacted Latosol Considering Physical and Dielectric Attributes

Soil strength is commonly related to both the state of stress and the degree of saturation to which the material is subjected. Studying these relationships helps us understand the behavior of unsaturated soils. In this research, the unsaturated strength of a compacted soil from the northeast region of Brazil was studied using unconfined compression tests and by considering physical and dielectric parameters. The study began by compacting samples at different energy levels, which had been dried or moisten in order to achieve targeted saturation degree values. This process was used to determine the soil-water characteristic curves and estimate the proposed dielectric indices. Finally, the specimens were subjected to unconfined compression tests. The results demonstrate that varying compaction energy levels have little influence on the unsaturated strength of the studied soil, which is reflected in the soil-water characteristic curve. Maximum strength was only observed when samples were tested close to their optimum moisture, regardless of compaction energy. Additionally, the results showed that the proposed methodology, which uses dielectric characteristics to estimate the unsaturated strength of the studied soil, not only presented high correlation coefficients but also proved to be easier to implement compared to using the soil friction angle due to suction, which is currently in practice.