Application of in-situ testing on cohesive soils

The last twenty years have been characterized by significant developments in the area of in-situ testing. The most relevant feature of this period is a better understanding of the relationships between the results of in-situ tests and basic soil behavior. This last fact has contributed to a remarkable rationalization of the interpretation of different kinds of in-situ tests and of the use of their results in design. The use of in-situ testing results in geotechnical design may be split into two distinct approaches; the direct approach which gives the opportunity to pass directly from in-situ measurements to the performance of foundation without the need to evaluate any intermediate soil parameters, and the indirect approach which leads to interpretation method that allow evaluation of the parameters describing the stress, strain, strength and consolidation behavior of soils. This paper presents interpretation of in-situ tests conducted in very soft/soft clay soil. Emphasis is placed on the cone penetration test (CPT), standard penetration test (SPT), vane shear test (VST) and unconfined compression test (UCT). Empirical relationships were developed to forecast shear strength from penetration resistance. The empirical correlation were compared with previously published data.