New perspectives in the interface shear strength characterization through the inclined plane test.

The assessment of the interface shear strength in multi-layer geosynthetic systems, such as the lateral barrier and the cover in landfills, is an important topic in the perspective of preventing any slip along the inclined surface. The Inclined Plane is recognized to be a very suitable and versatile test for monitoring interface strength under low normal stress. The test interpretation, ruled by the European Standard EN ISO 12957-2, is not fully accurate, as outlined by recent studies. Two alternative methods, the “Displacement” and the “Force” procedures, are proposed in the literature, in order to overcome the aforementioned limitations. In this paper a critical review of the available procedures in evaluating the interface shear strength is presented with reference to some tests carried out on typical geosynthetic interfaces. Furthermore, two different devices, available at LTHE (University of Grenoble) and ICEA (University of Padua) laboratories, are used and the test results compared.