PREFABRICATED VERTICAL DRAINS (PVD)
Prefabricated Vertical Drains (PVDs) or ‘Wick Drains’ are composed of a plastic core encased by a geotextile “filter jacket” for the purpose of expediting consolidation of slow draining soils .
Two main components of PVD serve the following functions .
• Core serves as a longitudinal flow path along the drain
• Filter jacket allows water to pass into the core while restricting intrusion of soil particles
MECHANISM:
As a result of the pore water pressures generated from the soil due to incoming load, water flows laterally to the nearest drain and discharge to the surface and thus accelerate primary settlement of the soil. These wick drains shorten pore water travel distance, reducing the loading time.
ADVANTAGES:
• Decrease overall time required for completion of primary consolidation due to preloading
• Permanent, continuous vertical drainage path with no discontinuities due to installation problems.
• Can withstand considerable lateral displacement or buckling under vertical or horizontal soil movement
• PVDs can be installed underwater and in a non-vertical orientation more conveniently
APPLICATIONS:
• Soil improvement of residential or construction areas
• The construction of infrastructure (roads, railways, harbours, airports)
• Construction of dams
• Land reclamation projects
