Formally a prefabricated vertical drain (PVD), it is a strip about 100 mm wide with a grooved plastic core wrapped in a nonwoven filter. A rig drives it down inside a steel mandrel on a grid, often 1 to 3 meters apart, then pulls the mandrel and leaves the drain. Pore water now has a short sideways path to the drain, so a surcharge fill can settle the clay in months instead of years.
Wick drains go in on a 1.5 meter triangle, then the surcharge sits until the settlement plates flatten out.
Also heard as
- PVD
- prefabricated vertical drain
- band drain
- strip drain
Related terms
Drainage
Carrying water along the plane of a geosynthetic to an outlet, as in wall backdrains and leak detection layers.
Filtration
Letting water pass across a geotextile while holding back the soil particles it carries.
Subgrade
Native or prepared soil surface on which a pavement, aggregate base or liner system is built.
Mud wave
Bulge of very soft soil shoved up ahead of fill being placed on weak ground.