Investigating Soil-Geogrid Interaction: Insights from Long-Term Pullout Tests

The study investigates the impact of soil confinement and interaction on the long-term tensile response of geosynthetics. To achieve this goal, a novel large-scale laboratory apparatus was developed; it allows us to investigate the pullout behaviour of geogrids embedded in a compacted granular soil and subjected to sustained tensile loadings. Comparisons between confined tensile strains and strains obtained from in-air tensile creep tests suggest that the creep reduction factor used in the limit state design approach may be conservative. Moreover, another key outcome of the research is the proposal of a procedure for determining the interface parameter necessary to design the length of the reinforcement. This procedure takes into account the viscous effects of polymeric materials under serviceability conditions during the design working life of the geosynthetic-reinforced soil structure.