Effects of Reinforcement type and Loading History on the Deformation of Reinforced Sand in Plane Strain Compression

To evaluate the effects of reinforcement type in terms of stiffness, viscous property, rupture strength, shape and loading history on the stress-strain behaviour during primary, sustained and cyclic loading of reinforced sand, a series of drained plane strain compression tests were performed on Toyoura sand. The sand specimens were reinforced with two types of polymer geogrid as well as two types of metal grid, having largely different stiffness values and surface conditions. Despite that the effects of reinforcement type on the overall stress-strain characteristics of reinforced sand and their rate-dependency are significant during primary loading, the effects are much smaller than the difference in the stiffness of reinforcement. The effects of reinforcement type on the global unloading behaviour and the residual strain by cyclic loading during otherwise global unloading are generally insignificant or negligible. The residual strains by cyclic loading of reinforced sand became substantially small by preloading as well as pre-sustained loading and pre-cyclic loading at higher load levels. With this procedure, polymer geosynthetic reinforcement, which is much more extensible and viscous than metal reinforcement, can be used to reinforce soil structures allowing very limited residual deformation.