The inclined plane device is specifically adapted to assess the geosynthetic interfaces friction under low confinement conditions. The lack of the standardized procedure proposed by the European standard (EN ISO 12957-2
2005) for the determination of geosynthetic interface friction properties has been proven by many recent researches available in the literature.
These researches demonstrated the need for revising the standard displacement procedure since it seems to be poorly suited for many geosynthetics interfaces and because the high sensitivity of the determined friction angle to test conditions.
Geosynthetics of reinforcement interface properties were determined by carrying out inclined plane tests under low confinement adapted to landfill covers conditions. Interface friction angles \( \left( {\varphi^{stand} } \right) \) were determined conformingly to the standardized displacement procedure and compared with those defined by a method known from the literature.
Then, interface friction angles were determined according to a new method called “tension procedure” which considers the measurement of the tension developed by the geosynthetic reinforcement during inclined plane tests.
Compared to previous data, the proposed method allows a new and more comprehensive interpretation of the inclined plane test since it pays attention to the different behavior of geosynthetics during tests.
This research demonstrates that the consideration of reinforcement tensions allows a more suitable comprehension of the mechanical behavior of soil-geosynthetic interface and a better representation of the in-situ behavior of the geosynthetic interface.
It appears that the mechanical behavior of the geosynthetic of reinforcement and the magnitude of the measured tension depended on the reinforcement characteristics specially the geosynthetic surface structure and the tensile stiffness (tensile modulus) J (kN/m).
The determined friction angles, both in static \( \left( {\varphi^{stat} } \right) \) and dynamic \( \left( {\varphi^{dyn} } \right) \) inclined plane conditions, are lower than those calculated using the previous methods which allow a more accurate design of landfill cover systems.
