Repeated shear behaviors of geotextile/geomembrane and geomembrane/clay interfaces

Because the normal stress applied to landfill liner systems increases with the volume of waste during the construction of engineered landfills, traditional shear tests do not adequately describe the loading process on the liner system because only one shear test is performed on a single sample. In this study, a series of laboratory tests using a new test method that differs from traditional shear tests were performed to investigate the repeated shear behaviors of geotextile/geomembrane (GT/GM) and geomembrane/clay (GM/clay) interfaces under various normal stresses. The test results indicated that increasing shearing times decrease the peak and residual shear strengths of both GT/GM and GM/clay interfaces. Additionally, the strength parameters obtained from traditional and repeated shear tests were both used to analyze global stability along the liner system of a typical landfill. The results of repeated shear tests and limit equilibrium analysis were determined to be significant for landfill liner system anti-slide design. The limitations of the tests were also discussed.