MODELING CHANGES IN GEOTECHNICAL PROPERTIES OF SOILS DURING WETTING: A METHODOLOGICAL APPROACH AND APPLIED RESEARCH (ON THE EXAMPLE OF SARZHYN YAR)

In the context of rapid urbanization and global climate change, predicting soil behavior under variable hydrogeological conditions has become increasingly relevant. This study investigates the impact of moisture content on the physical and mechanical properties of soils through numerical modeling using Plaxis software. The research focuses on evaluating deformation and strength characteristics of soil strata by simulating changes in the degree of saturation, which is crucial for engineering geology and geotechnical design in complex environments. The analysis is based on data from the Sarzhyn Yar area (Kharkiv, Ukraine), characterized by a pronounced gully-ravine landscape and variable groundwater depth. A stratigraphic model was developed and parameterized using the Mohr-Coulomb approach. Numerical simulations were conducted considering the dependence of key soil parameters—cohesion, internal friction angle, deformation modulus, and unit weight—on the degree of saturation (Sr). Empirical formulas were applied to represent moisture-dependent variations for different soil types (sandy loams, loams, clays, etc.). The results indicate that increasing Sr from 0.05 to 1.0 significantly alters the soil’s physical-mechanical properties, affecting the stress-strain state of the soil mass. Notably, when Sr approaches 0.65, a sharp increase in vertical settlements (Uy) and horizontal displacements (Ux) occurs, accompanied by elevated stress levels (σxx, σyy) and reduced strength, indicating decreased ground stability and heightened risk of foundation deformation. A sensitivity analysis of parameters c, φ, E, and γ was performed, enabling precise model calibration for specific geological conditions. This approach enhances prediction accuracy and allows adaptation to different water saturation scenarios. The practical application of the model demonstrates that ignoring moisture variation can lead to underestimated settlements and stresses, potentially resulting in premature structural degradation. Thus, the study highlights the importance of accounting for moisture-related risks in improving the reliability of engineering structures in areas with unstable hydrogeological conditions. The research contributes to the development of approaches for assessing soil stability in the context of anthropogenic pressure and climate change, with implications for infrastructure design in similar geological settings.