Geosynthetic interface friction using Force Procedure at the Tilting Plane.

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. Inclined Plane tests, using a Tilting Plane, are the most suitable tests for monitoring interface behaviour under low normal effective stress level. According to recent studies, the test procedure, ruled by the European Standard EN ISO 12957-2, could overestimate the interface friction angle between the geosynthetic surfaces. An original dual interpretation of this kind of test was recently proposed by the second and third authors: a complete understanding of a tilting test is based on the monitoring of the tangential displacement and/or of the force during the complete test. This new approach includes a light modification of the standard device. “Force Procedure” consists in measuring the force required to hold back the upper box. This contribution could allow a revision of the European Standard for Inclined Plane Test.