Enhancement in the interface shear resistance achieved by a novel geogrid with in-plane drainage

The enhancement in the interface shear strength achieved in the short-term by a novel geogrid, which combines both reinforcement and in-plane drainage functions, was studied. Marginal fill material (wet gravelly clay) was standard Proctor compacted to achieve 92% of its maximum dry unit weight and tested in the large shearbox apparatus under consolidated-undrained conditions. Overall, the interface shear resistance (τ_g-g) values mobilized for the novel geogrid were similar to the undrained shear strength of the test soil itself. In contrast, the τ_g-g values mobilized for a conventional geogrid, which had similar physical and tensile strength properties, were between only 82 and 85% of the undrained shear strength of the test soil. The benefit is that the increase in the interface friction angle (achieved by in-place drainage along the novel geogrid) will facilitate the use of some marginal fills, which may already be readily available onsite, in the construction of earth structures. Copyright ASCE 2008.