By Timothy D. Stark
Q: What design strength should be used for GCLs?
A: If the GCL is not encapsulated between two geomembranes, the slope design should/must assume that the GCL will be fully hydrated at a low normal stress (e.g., 5–10 psi for a liner system). If the GCL will be encapsulated between two geomembranes, the design strength can be assigned the average of the fully hydrated and as received moisture content strength envelopes. Another approach is to assume that some percentage of the GCL becomes hydrated and assign a hydrated strength to this percentage of the critical failure surface.