XVI Danube - European Conference on Geotechnical Engineering 07-09 June 2018, Skopje, R. Macedonia Paper No. 056 Abstract. Loose sands or very soft clays are sometimes hard to evaluate from geotechnical purposes with classical methods. The aim of the work is to estimate the applicability and reliability of some of the most popular relations derived from CPT in the case of marine sediments of Black Sea. The paper presents comparisons between values of main geotechnical parameters derived by well known formulas from CPT and laboratory tests executed on remoulded samples of such soils. In the first instance a classical soil behaviour chart was used in conjunction with grain size analyses. In the next step estimations of saturated or dry unit weights and friction angle of cohesionless submersed soils, based on well known relations was found in very good agreement with lab test values obtained from thin-walled tube samples. Finally, the evaluation of the state of stress puts in evidence that the investigated deposits are mainly under consolidate or normal consolidate and at least one of three different classical relations for the estimation of relative densities, fits well with values of lab tests. Keywords: Loose sands; Very soft clays 1 INTRODUCTION The aim of the work was to estimate the applicability and reliability of most popular relations derived from CPT tests in the case of marine sediments of Black Sea. The sampling and in-situ testing programme for the geotechnical site investigation consisted of drilling three boreholes to depths between 28 m and 34 m below seafloor (situated at about 51 m deep water). In two of it, CPTu tests has been performed using the down hole method, procedure which allow to collect also soil samples. A total number of 98 samples has been collected and several geotechnical lab tests has been performed on disturbed and remould samples: grain size distribution, unit and specific weight, Atterberg limits, oedometric compression, consolidation, hydraulic conductivity, direct shear test and triaxial compression. 2 SBT VERSUS GRAIN SIZE DISTRIBUTION Interpretation of CPT in the purpose of soil profiling is an important application of this in situ test, especially on those sites where soil sampling is a tough task, like wet or offshore areas, and in the last decades, dozens of specific soil behavior identification charts (SBT) developed in this trend. One of the most popular SBT chart is given by Robertson (1990), which provide a soil identification based on normalized cone resistance (Qt) related to the normalized friction ratio (Fr), which are both defined bellow: vo vo t t q Q ' ] [      (1) 100 [%] vo t s r q f F    (2) Comparison between soil properties derived from CPT tests and laboratory tests. STÃNCIUCU Mihaela 1 1 Ph.D. Eng.Geol., Assoc.prof.; University of Bucharest, Faculty of Geology and Geophysics, Traian Vuia st, No.6; stanciucumihaela@yahoo.com 529 https://doi.org/10.1002/cepa.725 wileyonlinelibrary.com/journal/cepa © Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin · ce/papers 2 (2018), Nos. 2 & 3