ABSTRACT
In the last decades, many researchers have investigated the properties of sands and clays, and they have published formulas, charts and tables as a general reference to support the design of geotechnical structures (e.g. Kulhawy & Mayne (1990)). Most general data refers to soil strength properties, such as a friction angle for sand or undrained shear strength for clay, which can be primarily used for stability analysis and ultimate limit state design (ULS). In contrast to ULS, serviceability state design (SLS) requires stiffness properties to be known. Several researchers have published correlations between stiffness and strength, index properties and/or state parameters. For sands, many correlations exist with the relative density, whereas for clay many correlations exist with the plasticity index.
