Geogrid-soil interaction: Experimental analysis of factors influencing load transfer

This paper presents interaction experiments with transparent soil to investigate the load transfer at the interface of different geosynthetic reinforcements. Microscopic interaction performance was evaluated in terms of mobilised tensile loads and interfacial shear stresses resulting from the relative movement between geosynthetic and soil. The effects of geogrid aperture size, tensile stiffness, geogrid type and reinforcement configurations on the load transfer were analysed. It was found that with increasing soil deformation, the contribution of friction to the total load transfer decreased and the transverse ribs were increasingly activated. The interfacial shear stresses were reduced as the ratio of geogrid aperture to mean particle size increased, resulting in lower geogrid loads. Higher geogrids loads were mobilised with increasing tensile stiffness of the reinforcement, but lower displacements of geogrid and adjacent soil occurred. Consistent results were found for woven PET and laid PP geogrids. The most effective load transfer was obtained for the aperture configuration with two closely spaced transverse members at each rib, as the soil particles were additionally confined. When the geogrid was attached to a nonwoven geotextile, the separation function was enabled, but the reinforcement performance of the geocomposite was lower due to reduced particle-aperture interaction.