Kinematic interface friction for geosynthetic liner on landfill slopes

The correct assessment of the interfacial properties between the geosynthetic surfaces in composite liner systems, as landfill covers, is an important issue to prevent the occurrence of potential slip surfaces. To characterize the geosynthetic friction, the Inclined Plane is recognized as a very suitable and versatile device, since it allows testing large samples with variable relative tangential displacements under low normal stress. According to recent studies, the test procedure, ruled by the European Standard EN ISO 12957-2 does not take into the account the real kinematic condition existing during the test. For this reason, two alternative procedures are proposed: the “Displacement Procedure” and the “Force Procedure”. In this study a full description of the three procedures is presented and an application to typical landfill barrier interfaces is carried out. Furthermore, several values of the interface friction angles are determined from the alternative methods and a comparison with the “standard” values is provided.