Microscale analysis of geomembrane–geotextile interface cyclic shear behavior using DEM

Given that the material-wearing process is the key factor influencing the dynamic shear strength at the interface between the geomembrane (GMB) and nonwoven geotextile (NWGT), this study investigates the cyclic shear behavior of the GMB–NWGT interface from a microscale perspective using the three-dimensional discrete element method (DEM). The textured GMB is simulated with breakable asperities and the thermally bonded NWGT is generated by spatially randomly distributed fibers which could be stretched and untangled. The established model is validated against the experimental data. The wearing process during cyclic loading is evaluated by quantifying the embedded depth of GMB asperities and fiber breakage within NWGT. The simulation results demonstrate that the maximum asperity embedment (inter-embedding effect), affected by the normal stress and displacement amplitude, induces the hook and loop interactions between asperities and fibers (inter-locking effect), accounting for the cyclic shear resistance at the interface. The inter-locking effect dominates the strain-hardening behavior of the GMB–NWGT interface when the percentage of inter-fiber bond breakage is less than 22% and the maximum asperity embedment ratio is lower than 60%; otherwise, the inter-embedding effect dominates the strain-softening behavior of the interface.