Determination of the Displacement of Shallow Foundations Sitting on Unsaturated Soils Using Analytical and Numerical Analysis Methods

The bearing capacity of a foundation is crucial for ensuring the stability and safety of structures. However, shallow foundations on unsaturated soils pose challenges due to the complicated behavior of such soils. To address this issue, engineers have developed analytical and numerical methods of analysis, which can be used to determine the bearing capacity of these foundations. This study explored the advantages and disadvantages of these methods, offering a thorough understanding of their role in ensuring the safety and longevity of structures built on unsaturated soil. The analysis in this study was conducted using finite element method simulations on soil sections with varying groundwater levels and degrees of saturation. The results obtained from PLAXIS 2D simulations revealed the effects of fluctuations in groundwater levels and changes in saturation degree on foundation displacements, emphasizing aspects often overlooked in empirical approaches. Under unsaturated conditions, as the degree of saturation decreased, the soil was better able to maintain its structural integrity, resulting in reduced foundation displacements. However, at near-complete saturation (%99), displacements increased significantly, highlighting the risks to foundation stability in soils with high saturation levels, particularly in flood-prone areas. Variability in excess pore water pressure in sections with high saturation indicated potential soil instability under high stresses, impacting structural integrity. Furthermore, finite element analyses showed that classifying soil as drained or undrained impacted foundation displacements. In conclusion, the comprehensive analysis provided by numerical methods emphasized the limitations of empirical approaches and underscored the importance of advanced simulation tools in modern geotechnical practices.