ABSTRACT
Biaxial geogrids are often used to reinforce unpaved roads over low strength subgrades. By allowing the unsuitable subgrade to remain in place and allowing for reduced road thicknesses, substantial reductions in cost and improvements in performance can be achieved. This paper reviews research undertaken at Technological University Dublin where small model testing boxes and instrumented geogrids have been used in combination with representative samples of weak subgrades and high-quality granular fill to simulate the response of biaxial geogrids to monotonic and cyclic plate loading. It was found that the tensile strain measured in the geogrid under test was only a small fraction of the geogrid's ultimate tensile strain, indicating that the ultimate strength of the geogrid is less important than its interaction with the fill. The magnitude of loading was found to have a more significant effect on displacement than the number of load cycles suffered. It was also found that increasing the number of geogrids in the road had a very significant impact on strain and displacement suffered.
