Angle-based residual strength estimation of geotextile/textured geomembrane interface

Geotextile and geomembrane are widely used in landfill liner systems, but the relationship between geomembrane roughness and geotextile/geomembrane interface residual shear strength remains to be studied. In this paper, by using a large-scale ring shear apparatus, a series of ring shear tests of geotextile/geomembrane interfaces were conducted, and the profile inclined angle distributions of the textured geomembrane surfaces were obtained by a profilometer. The experiment results showed that the geotextile/geomembrane interface reached residual strength after a shear displacement of 3 m, and the average inclined angle of the textured geomembrane was close to zero. With the increase of geomembrane asperity height, the interface residual strength increases. Through force analysis and statistical analysis, quantitative relationships between residual shear strength of geotextile/co-extruded geomembrane and geotextile/cone-shape structured geomembrane interfaces and inclined angle distribution were established. The model was validated by test results and case analysis. This study helps to understand the mechanism that causes the textured geomembrane to generate high interface residual strength.