Geosynthetics in foundation beds demonstrate their beneficial effects only after considera-ble settlements, since the strains occurring during initial settlements are insufficient to mobilize signifi-cant tensile load in the geosynthetic. Prestressing the reinforcement is a promising technique to overcome this shortcoming. This paper presents results from a series of finite element analyses carried out to inves-tigate the improvement in bearing capacity of a footing resting on geogrid reinforced foundation bed overlying weak ground due to prestressing the reinforcement. The results of finite element analyses are validated by carrying out a series of laboratory scale loading tests. The parameters varied are magnitude of prestress, relative density of foundation bed etc. The effects of prestressing on the interface shear strength between geogrid and granular soil are studied by carrying out large scale direct shear tests in a shear box of dimensions 300 x 300 x 200 mm. It is observed that the bearing capacity and settlement behaviour of footings can be considerably improved by prestressing the geosynthetic reinforcement in the foundation bed. The interface shear strength between geogrid and granular soil is considerably influenced by the magnitude of prestress.
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