Comparison between 2d and 3d behavior of sheet piles by finite element method

In many cases, two dimensional (2D) idealizations of what are essentially three dimensional (3D) problems may not produce reliable results. Whereas highly realistic 3D analyses might not have been within the reach of the practicing geotechnical engineer in the past, developments in numerical technology are changing this situation and bringing realistic 3D analysis within the reach of the practicing engineer. The conventional methods, based on the limit equilibrium approach, are commonly used in the design of sheet pile walls. This paper presents a series of 3D numerical analysis performed by the finite element method (FEM) on sheet piles in a loose sandy soil, and the effect of different length to height ratio of sheet piles on maximum bending moment, lateral earth pressure and sheet pile hinge point position was obtained. The purpose of 3D finite element method simulations was to investigate the soil-sheet pile interaction mechanism by comparing the finite element modeling comprising 2D plane strain analysis of sheet pile walls. The results indicate that, in sheet piles with length to height (L/H) ratio less than 1, 2D analysis is very conservative in comparison with 3D analysis. On the other hand, for the L/H ratio more than 5, there seems to be a threshold value of 3D to 2D finite element method results beyond which the ratio of 3D to 2D analysis became insensitive to any increase in L/H ratio.