The liner or fabric runs over the crest, along a short runout, then down into the trench, which is backfilled and compacted to lock it in. Trench size and runout length are designed together so the anchorage holds the panel during placement and covering without tearing it. Trench corners are rounded so the sheet is not creased or overstressed.
Don't backfill the anchor trench until the sheet cools off this evening, or it'll pull tight overnight.
Backfill anchor trenches when the sheet is at its coolest, usually early morning, so it is not locked in while expanded and then pulled tight as it cools.
Also heard as
- anchorage trench
- key trench
Related terms
Runout
Flat length of geosynthetic between the crest of a slope and the anchor trench.
Geomembrane
Low-permeability polymer sheet used as a liquid or gas barrier in liners, covers, ponds and tunnels.
Trampolining
Geomembrane pulled tight across a corner or the toe of a slope, leaving a gap underneath like a trampoline.
Panel
One continuous piece of geomembrane as deployed, numbered and tracked through seaming and testing.