Peak friction values for textured HDPE

From the GMA Techline

RE: Peak friction values for textured HDPE?
I am currently in the design phase of a landfill cover system that I would like to design with rather long 3:1 slopes consisting of an HDPE liner and geocomposite drainage net atop the waste and under three feet of cover soil. I am in need of friction angles for HDPE (textured) liner, similar to the ones presented in Figure 5.7 of Dr. Koerner’s book, for the geomembrane-to-geotextile and geomembrane-to-soil interfaces. Can you point me in the right direction? Any information would be greatly appreciated.

(Greg | Montana)

Reply: The official answer is that you have to test the interface of the specific HDPE-T with the specific NW-NP fabric on the composite at the site-specifc conditions.

The unofficial answer (from our database) is peak friction of 25 deg and peak adhesion of 8 kPa. For residual, peak friction is 17 deg with zero adhesion. Now don’t go getting me in trouble for giving you these values and then having a failure, but I do think they are reasonable.

Bob Koerner | GMA Techline