## 4 Conclusions  
Despite many proposals for determining the shear strength parameters of soils based on the results of static CPTU probing, this problem has not been sufficiently solved. There exists extensive literature on this subject [9; 29; 30; 31], but all of the proposed methods seem to not be sufficiently tested by authors on anthropogenic soil from Cracow (Poland). The failure envelope in non-cohesive soils with a small amount of fine fractions (silt or clay) generally passes through the origin in the \(\tau\)-\(\sigma^{\prime}\) plane for most normally consolidated soils, suggesting \(c^{\prime}\) = 0 [kPa]. In the authors' opinion, the high cohesion value obtained in the tests indicates a case of cemented soil. A cementation process occurred in the tested soil, because the soil consisted of suspended particles of carbonate calcium CaCO\({}_{3}\). Moreover, the shear strength parameters were significantly better correlated with the corrected cone resistance qt than with the normalised friction ratio Fr tested soil (Tables 1 and 3). This has also been confirmed by numerous studies, presenting relationships more frequently utilising the cone resistance value [9]. Correlation for effective friction angle \(\varphi^{\prime}\) [deg] (Equation (5))  
\[\varphi^{\prime}=3.49\cdot\log_{10}(q_{t})+30.61\ \ \left(\text{R}^{2}=0.81\right) \tag{11}\]  
Correlation for effective cohesion \(c^{\prime}\) [kPa] (Equation (8))  
\[c^{\prime}=-15.98\cdot\log_{10}(q_{t})+18.01\ \ \left(\text{R}^{2}=0.82\right) \tag{12}\]  
Due to small differences in the value of the determination coefficient R2, the authors do not exclude the possibility of using the simplest linear dependence correlation for effective friction angle \(\varphi^{\prime}\) [deg] (Equation (6))  
\[\varphi^{\prime}=0.84\ (qt)+29.83\ \ \ \ \left(\text{R}^{2}=0.79\right) \tag{13}\]  
and linear dependence correlation for effective cohesion \(c^{\prime}\) [kPa] (Equation (9))  
\[c^{\prime}=-3.89\ (q_{t})+21.76\ \ \left(\text{R}^{2}=0.81\right) \tag{14}\]  
The presented equations are original functions depicting the relationship between the results of static CPTU probing and the geotechnical parameters of anthropogenic ground substrates deposited in the \"White Seas\" settling tanks in Krakow. The statistical relationships presented in the article may serve as a basis for estimating, based on established equations, the strength parameters for the examined anthropogenic subsoil. The obtained functional relationships will enhance the process of subsoil recognition on these waste soils. They can be utilised in conceptual and design work for future construction investments on the approximately eighty hectares of the \"White Sea\" area in Cracow. They may also allow for the specification of more detailed criteria regarding the protection of existing structures during the exploitation phase. The derived correlation relationships are based on local data. These are waste soils. The scope of application of correlation relationships is limited to anthropogenic soils of the same chemical composition. As shown in Figures 7 and 8, the tested soil consists of only one mineral calcite (CaCO\({}_{3}\)) and has a specific grain size range. The correlation formulas that were obtained can only be applied to such soils. They will not give positive results for other soils. The proposed correlations give cautious values of the drained strength parameters, which can be used as a first approximation for use in preliminary design of geotechnical structures. Furthermore, the proposed correlations should only be used in cases where time and cost constraints do not allow for actual effective strength tests to be carried out. In most other cases, the use of effective strength tests will provide a much more reliable and cost-effective estimate of the strength properties of the soil in question. Conceptualization, J.Z. and E.P. ; methodology, E.P. ; software, J.Z. ; validation, J.Z. and E.P. ; formal analysis, E.P. ; investigation, E.P. ; resources, J.Z. ; data curation, J.Z.