2D AND 3D FEM ANALYSIS IN GEOTECHNICS: WHEN DOES THE THIRD DIMENSION MATTER?

Finite Element Method (FEM) is widely used in geotechnical engineering for analyzing soil-structure interactions, slope stability, and foundation performance. While 2D FEM is a common approach due to its efficiency and simplicity, 3D FEM provides a more realistic representation of geotechnical problems by incorporating the third spatial dimension. This study compared the results of 2D and 3D FEM analyses to determine whether the inclusion of the third dimension significantly affects computational outcomes for the same geotechnical model.

To investigate this, two case studies are conducted: (1) a slope stability analysis in both 2D and 3D, and (2) a settlement analysis in both 2D and 3D. The results show that problems that inherently follow a 2D assumption, such as slope stability, 3D modeling does not provide significant advantages, making 2D analysis a sufficient and efficient approach. However, settlement analysis is inherently a 3D problem due to stress distribution and spatial soil deformations, meaning that a 2D model cannot accurately capture real behavior.

The study highlights the importance of choosing the appropriate FEM approach based on problem characteristics. While 2D FEM remains a powerful tool for many geotechnical applications, complex deformation patterns and anisotropic effects in problems like settlement require 3D modeling for accurate predictions. These findings provide engineers with practical guidelines for optimizing computational resources while ensuring reliability in geotechnical design.