Wick drains, Prefabricated vertical Wick drain
Wick drains, also known as Prefabricated Vertical Drains (PVD) and
Vertical Strip Drains (VSD), are a ground improvement technique
that provides drainage paths for pore water in soft compressible
soil, using prefabricated geotextile filter-wrapped plastic strips
with molded channels. A hollow mandrel is mounted on an excavator
or crane mast. The wick drain material, contained on a spool, is
fed down through the mandrel and connected to an expendable anchor
plate at the bottom of the mandrel. A vibratory hammer or static
method is used to insert the mandrel to design depth. The mandrel
is then extracted leaving the wick drain in place. The wick drain
is then cut at the ground surface, a new anchor plate is connected
to it and the mandrel moved to the next location. A pattern of
installed vertical wick drains provides short drainage paths for
pore water, thereby accelerating the consolidation process and the
construction schedule.
