Site characterization can be defined as the process of identifying the geometry of relatively homogeneous zones, the groundwater table and defining index, strength, and stiffness properties for the soils within these zones. The fundamentals for predicting the geomechanical behaviour of soils by means of in situ tests have been developed for conventional soils: reconstituted sands and reconstituted and isotropically consolidated saturated clays. The behaviour of unusual soils such as tropical, residual, intermediate soils, and tailings dams is being developed. The geomechanical behaviour of conventional soils such as sedimentary soils are based on the stress history, while for unusual geomaterials, such as tropical soils, it is characterized by bonding and structure, and by anisotropy as well as by the unsaturated condition. It is important to understand the behaviour of tropical soils since they cannot be correctly predicted by models and correlations developed by Classical Soil Mechanics. In this scenario, identifying the unusual soil behaviour is the first step of the site characterization program, since it can lead to greater or lesser applicability of classification methods and in the estimative of geotechnical parameters. This paper presents the basics of the behavioural classifications used to interpret CPT and DMT and discusses their applicability to tropical soils, especially those of pedogenetic evolution and sandstone residuals such as those that occur in the experimental research sites of USP São Carlos and Unesp Bauru. Laboratory (triaxial and consolidation tests with controlled suction) and in situ tests (CPTu and SDMT) were carried out at different periods of the year to better understand the soil behaviour and site variability. Classifications and correlations to estimate soil parameters from CPTu and SDMT are assessed, first to define the unusual soil behaviour, and then compared with laboratory test data. New classification criteria, based on the relationship between elastic parameters of small (G0) and large (qc, N60, ED, MDMT) strain determined by in situ tests are presented to identify the presence of microstructure and the effect of the unsaturated condition, and the advantages of using them to better characterize the site profiles of unsaturated tropical soils are discussed.