Testing Biaxial Geogrids for Specification and Design Purposes

The use of biaxial geogrids has rapidly increased in recent years. Their ability to resist biaxially applied loads and strains is critical to their success. However, standard test procedures are essentially restricted to uniaxial testing and conventional analytical techniques do not easily allow the load-strain characteristics of the materials in two orthogonal directions to be mathematically combined. In this paper testing techniques are described which allow characterisation of the tensile ribs and junctions forming the geogrids and allow biaxial testing of the overall structures. It is suggested that the combination of these testing techniques and new analytical methods provides the means to more appropriately specify and represent the operational behaviour of biaxial geogrids in design.