Appraisal of Anchor Arrangement and Size on Sand-Geogrid Interaction in Direct Shear

Soil-reinforcement interaction is a major factor in the analysis and design of reinforced earth structures. In current research the effects of attaching elements of different size and numbers as anchors on enhancement of interaction at soil-geogrid interface under direct shear conditions were studied. Poorly and well graded sands (S-C & S-f), a high density polyethylene geogrid, anchors with three different size and numbers (layouts) and clamping length of 2 cm from shear surface were used. Samples were prepared dry at a relative density of 80% in a 30 x 30 cm direct shear box and subjected to normal pressures of 12.5, 25 and 50 kPa with the shear load applied at a rate of 1 mm/min. Results of the assessment show that anchored geogrids improve shear resistance at interface mainly due to mobilization of passive soil resistance that is significantly influenced by the magnitude of the normal pressure and the number and size of anchors. Interaction enhancements achieved varied between a minimum of 8% and a maximum of 42%.