Soil Arching Effect in Earth Embankment

Soil arching phenomenon plays an important role in distributing the stresses through earth embankments in the presence of stiff deep foundation system. The mass of soil at the lower stiffness zone tends to yield and deform, while the stiffer zone will oppose this deformation causing additional soil pressure. The type of soil arching can be distinguished depending on the compressibility of the structure and the surrounding soil. The current study investigates the performance of two embankments rested over the ground surface underlain two combined pile caps spaced by 32.0 m center-to-center that are used to support the vertical loadings of two piers of a roadway bridge. The soil arching effect is evaluated at short-term and long-term conditions due to the presence of a layer of soft compressible soil in the native ground. Three-dimensional numerical analysis was conducted on 5.5 m high embankments rested over zones with different vertical stiffnesses. The purpose of this study is to evaluate the performance of the embankments through long-term deformations in addition to the additional induced axial loads on the deep foundation system resulting from soil arching phenomenon in the embankments. The results demonstrates that the vertical arching factor over the combined pile caps increased from 1.69 just after construction to 1.82 at the end of 90% consolidation of the soft layer. In addition, the serviceability limit state of the earth embankment was controlled by the longitudinal settlement trough of the embankments to meet the current design codes limitations.