Frictional behaviour of three critical geosynthetic interfaces

This paper’s scope is the shear interaction mechanisms of three critical geosynthetic interfaces (geotextile/geomembrane; drainage geocomposite/geomembrane and soil/geomembrane) typically used for lined containment facilities such as landfills. A large direct shear machine was used to carry out 159 geosynthetic interface tests. The results showed strain softening behaviour, a very small dilatancy, 0.1–1 mm, and non-linear failure envelopes at normal stress range of 25–500 kPa. The three types of interfaces present the same main interaction mechanisms: interlocking and friction. For geotextile/geomembrane and drainage geocomposite/geomembrane interfaces, the higher the asperity height, the higher the interface shear strength.Whereas for soil/geomembrane interfaces, the higher the soil shear strength, the higher the interface shear strength. The drainage geocomposite/geomembrane interface showed the lowest friction angles, followed by the geotextile/geomembrane and the soil/geomembrane interfaces

Shear strength behavior of geotextile/geomembrane interfaces

This paper aims to study the shear interaction mechanism of one of the critical geosynthetic interfaces, the geotextile/geomembrane, typically used for lined containment facilities such as landfills. A large direct shear machine is used to carry out 90 geosynthetic interface tests. The test results show a strain softening behavior with a very small dilatancy (<0.5 mm) and nonlinear failure envelopes at a normal stress range of 25-450 kPa. The influences of the micro-level structure of these geosynthetics on the macro-level interface shear behavior are discussed in detail. This study has generated several practical recommendations to help professionals to choose what materials are more adequate. From the three geotextiles tested, the thermally bonded monofilament exhibits the best interface shear strength under high normal stress. For low normal stress, however, needle-punched monofilaments are recommended. For the regular textured geomembranes tested, the space between the asperities is an important factor. The closer these asperities are, the better the result achieves. For the irregular textured geomembranes tested, the nonwoven geotextiles made of monofilaments produce the largest interface shear strength