Utilization of a Large-Scale Testing Apparatus in Investigating and Formulating the Soil/Geogrid Interface Characteristics in Reinforced Soils

2 Abstract: A laboratory study was carried out using a large-scale universal testing apparatus to investigate the controlling factors affecting soil/geogrid interface shear strength, and conclude a representative mathematical formula for its prediction. The testing apparatus accommodates soil samples up to 1.0 m , 3 and could perform direct shear tests on soils, pullout tests of geogrid sheets from soils, and uniaxial tension tests on the geogrid sheets without soils. D ifferent types of geogrids, and punctured geomembranes sheets of different holes sizes were used in the testing program. Two different grain size distributions of cohesionless soils were also used in the testing program. The effect of the soil grain size distribution, its shear strength, dilatancy effect, geogrid surface configurations and material extensibility were investigated on the soil/geogrid interface shear strength. The results of the testing program as well as data reported in the literature were implemented to develop a formula to predict the soil/geogrid interface shear strength after incorporating the controlling factors.