A numerical study to evaluate the impact of suction on geotechnical structures

The unsaturated ground may be subject to significant deformations due to seasonal variations. These deformations affect the performance of structures such as shallow foundations, pavements, embankments, unsaturated slopes, and buried pipelines. Therefore, appropriate investigations are needed to understand the response of these structures during drying and wetting cycles. Different matric suctions may develop during these alternate cycles, impacting a structure�s long-term performance. Hence, 2-dimensional finite element simulations have been performed with a coupled pore pressure-deformation analysis to study the impact of suction variations in strip foundations and pavements with the unsaturated subgrade. These simulations were carried out in the ABAQUS code. The stiffness and shear strength of the soil vary with the suction during drying and wetting. These variations were incorporated in the material model (Mohr-Coulomb) through a user-defined subroutine USDFLD. The numerical results of the strip footing model are compared with the available literature for different developed suctions in the footing soil. Further, this study presents the impact of matric suction and groundwater table depth on the responses of a flexible pavement subjected to cyclic wheel loads. The results indicate that the maximum vertical deflection increases up to 43.2% when the subgrade is fully saturated from an initial GWT depth of 5m with an initial suction of 5000kPa.