Experimental Investigation of Geogrid Response Under Multi-axial Loading

Abstract

Geogrids are widely used to stabilize and reinforce geotechnical infrastructure systems such as retaining walls, slopes, and unpaved/paved roads. The performance of geogrid-stabilized roads depends on several factors including the gradation of the unbound aggregate layer, the geogrid aperture size distribution and radial stiffness, and the stiffness of the subgrade layer amongst other factors. To investigate the performance of geogrid-stabilized pavement systems, particularly those using multi-axial geogrids, a new experimental device capable of conducting multi-axial tensile tests to determine radial stiffness under multi- axial loading has been developed. The device incorporates six load frames and jacks (3 pairs) to apply in- plane tensile forces. Depending on the number and orientation of the load frames and jacks, uniaxial, biaxial and triaxial loading configurations can be achieved by applying selected radial forces. In addition to in-plane tensile testing, the test system includes a soil box with a vertical reaction load frame to enable cyclic plate load testing of an embedded geogrid specimen. In the present study, results from multi-axial in plane tensile tests are compared with uniaxial tensile tests. The ability to test geogrids and geogrid-aggregate systems in different radial and out-of-plane loading conditions shows the potential challenges of relying on uniaxial test results only.