Numerical Investigation of the Effect of Using Geofoam on Static and Dynamic Earth Pressures Affecting Retaining Structures

Many factors affect the design of retaining structures, such as soil properties, structure geometry, groundwater level, surcharge loads, and dynamic loads. Many studies show that the dynamic loads affecting the retaining structure decrease when geofoam materials, which have increased in use as structural materials in recent years, are used behind retaining structures. However, these studies focused mostly on the effects of geofoam material properties. In this study, the effect of geofoam material on the lateral earth pressure caused by static and dynamic loads was investigated when retaining structures of different geometries were constructed. Retaining structures in different geometries were analyzed with the help of the Plaxis program based on the finite element method. The results showed that increasing geofoam thickness behind retaining walls reduced both wall deformations and lateral earth pressures under static and dynamic loadings, with minimum deformations observed at t/H ratios of 0.4 and 0.3, respectively. Optimum geofoam thickness for reducing dynamic earth pressures varied with wall height, being approximately t/H = 0.8 for 3 m, 0.7 for 4.5 m, and 0.6 for 6 m walls, with greater effectiveness at upper wall levels for taller structures. In addition, it has been observed that as the thickness of the geofoam material used behind the retaining structure increases, the dynamic pressures affecting the retaining structure decrease significantly.