Based on the results of dynamic probing (DP), time-domain reflectometry (TDR/MUX/MPTS), resistivity cone penetration tests (RCPT), Marchetti dilatometer tests (DMT), and seismic dilatometer tests (SDMT), it is possible to develop a relationship to calculate the relative density (D_r) and degree of saturation (S_r) of selected sandy soils. Compiled databases from documented research points for selected sandy soils were used to construct and develop direct correlations between the measured pressures p₀ and p₁ from DMT and shear wave velocity (V_s) from SDMT, along with pore water pressures (u₀) and atmospheric pressure (Pa). The results allowed us to make a preliminary prediction when evaluating the parameters. Further, they allowed limiting the use of an additional device, especially in the case of multilayer heavy preconsolidated subsoils. Moreover, soil physical and mechanical characteristics (temperature, humidity, pressure, swelling, salinity) measured from TDR/MUX/MPTS (laboratory/field-operated meter for simultaneous measurements of soil moisture, matric potential, temperature, and salinity—bulk electrical conductivity) were assessed. The main achievement of this paper is the original proposal of using a new nomogram chart to determine the relative density and degree of saturation based on DMT and SDMT tests.

The realisation of construction objects in the immediate vicinity of flood embankments is among the most demanding engineering processes. All earthworks, drainage, and structural works carried out near the embankments can affect the stability of slopes, filtration conditions, changes in groundwater levels, and local ground loosening. For this reason, it is essential to apply appropriate design, execution, and monitoring methods based on reliable geotechnical reconnaissance and proper implementation procedures. The article presents an analysis of the process of constructing a retention reservoir located near a flood embankment. Particular attention was paid to the impact of executing deep excavations secured with a system of retaining walls on the existing hydrotechnical structure. Based on the analyses conducted, the process of implementing the entire construction project was assessed, considering the potential for failures during and after the investment. A block diagram of the potential construction failure mechanism during the realisation of the retention reservoir near the flood embankment was also proposed. The retrospective EC7-II HYD screening gave ΛHYD = 2.84–3.47% for the S_k/W′_k formulation, 58.44–71.42% for the u/σ_v formulation, and 2.89–3.53% for the Δu/σ′_v formulation under VC2(a). Under VC2(b), the corresponding values were 2.69%, 55.31%, and 2.74%. The governing value was ΛHYD = 71.42%, below the 100% worksheet acceptance criterion.

According to Eurocode 7, limit state design codes generally draw more attention to ultimate limit states than to serviceability limit states. This paper presents the problem of settlement assessment of spread foundations on clays when the foundation design is governed by the serviceability limit state requirements. The paper presents the test results of geotechnical parameters for heavily preconsolidated boulder clays (sandy clay saCl and silty sandy clay sasiCl), which prevail on the Warsaw University of Life Sciences – SGGW campus. The test results were used for settlement calculations of spread foundations. Based on the results of field and laboratory tests, the problem of spatial variability assessment and determination of the characteristic value of soil parameters was addressed. Classical statistics and Bayesian analysis were used in the statistical analysis of the test results. Settlements of spread foundations were calculated based on the soil parameters obtained from cone penetration tests (CPTs) and dilatometer tests (DMTs). Special attention was drawn to the selection of the characteristic values of soil parameters. Determination of the characteristic value of the constrained modulus M _k was performed using two methods: according to the well-known and frequently used formula proposed by Schneider (1997; 1999) and according to the European draft standard prEN 1997-1:2022-09. Settlement calculations of spread foundations were carried out taking into account changes in the stresses and the constrained modulus in the subsoil. The calculated settlements were verified by field measurements performed during the construction of the object. Comparison of settlements obtained from the characteristic values of the constrained modulus M _k estimated according to prEN 1997-1:2022-09 with the measured settlements indicates that the calculated values were significantly higher than the measured values. Smaller differences between the measured and calculated settlements were obtained when the characteristic values of the constrained modulus M _k were determined from Schneider's formula, while smaller differences were obtained when the mean values of the constrained modulus M _mean were used.