Use of GCL to mitigate shear-induced damage to geomembrane from gravel in underlying compacted clay

Liner systems for landfills and heap leach pads are often constructed with compacted clay liners (CCLs) containing significant amounts of gravel. A geomembrane placed against a gravelly CCL can be vulnerable to damage under conditions of high overburden stress combined with interface shear displacement. Large-scale shear tests were conducted over a wide range of normal stress for smooth HDPE geomembranes over CCLs containing 20% angular gravel. Replicate shear tests were also conducted with a geosynthetic clay liner (GCL) in between the geomembrane and CCL to evaluate protection provided by the GCL. Results indicate that shear displacement between a geomembrane and a gravelly CCL under high normal stress conditions can cause severe damage to the geomembrane. Results also indicate that placing a GCL under the geomembrane can greatly reduce such damage.