Abstract: Reinforced soil is being extensively used for various Ground Improvement applications due to its effectiveness and durability. The load-settlement behaviour of Reinforced Soil depends upon the interaction between the reinforcement and surrounding granular soil. This paper investigates the effect of gradation of surrounding soil on the interface shear parameters, by carrying out a series of large scale direct shear tests using a shear box of dimensions 300 x 300 x 200mm.Tests were conducted on five no coarse aggregate (CA) and sand (S) with varying mix ratio of 1:0.5, 1:1, 1:1.5 and 1:2and separately for coarse aggregate and sand also. It is observed that gradation of soil, shear parameters and aperture of Geogrid considerably influences the interface shear parameters between the Geogrid and surrounding soil.

Keywords: Reinforced Soil, Load-Settlement Behaviour, Gradation, Interface Shear Parameters.