Selection of Geosynthetic Reinforcement Stiffness for 3D Numerical Modeling of GRS Abutments under Service Load Conditions

Conventional numerical modeling of geosynthetic-reinforced soil (GRS) abutments assumes that reinforcement has constant stiffness derived from constant-rate-of-strain (CRS) tensile tests, neglecting the creep behavior exhibited by materials such as high-density polyethylene (HDPE) geogrids under field conditions. To evaluate the impact of creep behavior of HDPE geogrids on the static response of GRS abutments, a three-dimensional (3D) numerical model was developed, incorporating three modeling approaches for geosynthetic reinforcement stiffness: (1) constant stiffness neglecting creep (i.e., CRS stiffness), (2) constant secant creep stiffness, and (3) nonlinear creep stiffness using a hyperbolic formulation. The results indicate that neglecting creep behavior leads to an overestimation of geosynthetic reinforcement stiffness, resulting in underestimation of deformations and reinforcement strains while overestimating reinforcement tensile forces and required tensile strength. Notably, the GRS abutment with nonlinear reinforcement creep stiffness yields results comparable to those obtained with constant stiffness derived from constant-load creep tests, with the latter offering slightly more conservative predictions. These findings provide practical guidance for selecting appropriate reinforcement stiffness models to improve the accuracy of GRS abutment performance predictions under service loading.