Seasonal variability in CPT: The influence of unsaturated condition in a tropical soil site

The interpretation of cone (CPT) and piezocone (CPTu) penetration tests is well-established for soils that follow the classical Soil Mechanics. The literature on the interpretation of these tests performed in unsaturated tropical soils is limited. CPT data are presented and discussed to show the influence of seasonal variability in an unsaturated tropical soil site. The peculiarities and implications of such variability are discussed based on the principles of Unsaturated Soil Mechanics. The test data showed that soil suction significantly influenced CPT data up to 4.0 m depth at the study site. It shows the importance of considering seasonal variability in unsaturated soil sites, not only considering the change in water content, but also considering the soil suction and the soil-water retention characteristics. It is important to consider this aspect in the interpretation of CPT data and in the estimation of the geomechanical parameters of these soils.