Landfill Liner Slope Stability (Static & Seismic)

[Geotech_Pavement]

Is anyone familiar with adhesion and interface friction shear strength properties obtained from interface shear tests (large scale sandwich tests using soils and geosynthetics) ?
We use these interface shear strength properties for landfill liner-soil slope stability.

I want to know if it is normal or unconservative to use interface adhesion/cohesion shear strength for slope landfill liner-soil slope stability. I always thought it was normal to only use interface friction angle for landfill slope stability. Curious to hear your thoughts.

Thanks

Alex

 

[zelgar]

You need to consider all of the failure modes, as the slope failure may occur in the waste itself. It doesn't do you any good to have a liner (cap or bottom) that is stable if the underlying material (soil for bottom liner, waste for cap) if the failure mechanism will occur in the materials you didn't evaluate.

 

[GeoEnvGuy]

I read the books by Koerner and other work about adhesion but I have no faith in designing a slope which relies on material sticking by adhesion to a geosynthetic which degrades. Usually consider a discount on the friction angle of triaxial or shear box tested material or a literature value interface friction angle between material and the geosynthetic for a landfill cover.