An experimental investigation into the load transfer mechanisms in anchored geosynthetic systems.

Abstract

An experimental investigation of the load transfer mechanisms in anchored geosynthetic systems has been performed. The objective of the research was to evaluate the ability of these systems to effectively apply a compressive load to cohesionless soil. Laboratory tests were conducted to investigate the load transfer mechanisms at the following three interfaces: (1) the anchor-soil interface, (2) the anchor-geosynthetic interface, and (3) the geosynthetic-soil interface. Cyclic pullout tests on ribbed anchors were conducted to study anchor-soil interaction. In dense sand a high interface friction developed during initial driving. However, upon load reversal it decreased by approximately 50%. Extreme degradation of the interface friction resulted with continued cycling. In loose sand, the maximum interface friction was approximately equivalent to the residual shear strength of the sand. The residual interface friction was about 50% lower than the maximum interface friction. Anchor-geosynthetic connection tests and wide-width tensile tests yield similar fabric strengths as long as the geosynthetic is firmly clamped in the connector. However, for a woven geosynthetic, where the weave can separate, a reduction factor had to be applied to the standard wide-width tensile test to predict the connection strength. Geosynthetic-soil deformation tests were conducted to determine the magnitude and distribution of the vertical stresses applied to the soil at the geosynthetic-soil interface. While significant soil stresses were observed in the vicinity of the anchor, they diminished rapidly with radial distance from the anchor. Finally, plastic yielding of the geosynthetic, combined with anchor uplift, may reduce stress in the system and thereby compromise the overall effectiveness of anchored geosynthetic systems in transferring load to the soil.