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Prefabricated Vertical Drains (PVDs)

It is also a geocomposite consisting of plastic core and surrounded by non woven. These are held vertically in soils for drainage. Plastic core forms a channel for water movement, while outer geotextile fabric helps in filtation. The flexible core is typically manufactured of polypropylene and both sides have grooves allowing water to flow unimpeded. The core is wrapped in a strong and durable geotextile filter fabric with excellent filtration properties, allowing free access of pore water into the drain. This also prevents piping of fines from adjacent soils without clogging.

The drain is fed down through a hollow mandrel mounted on an excavator or crane mast, connected at the bottom to an expendable anchor plate. A vibratory hammer or static method is used to insert the mandrel to design depth. It’s then removed, leaving the wick drain in place. The wick drain is then cut at the ground surface, a new anchor plate 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, which accelerates the consolidation process and the construction schedule.
The Bombay Textile Research Association (BTRA), a pioneer textile research institute over the 65+ years, was established in 1954 by Govt. of India along with the industry association to boost research, conducting testing, consultancy and certification in the field of textile, polymers, fibers and other materials.
Following are the tests done at BTRA for PVDs

  • Width
  • Weight per Linear Metre
  • Tensile Strength & Elongation (Wide Width) [ASTM D: 4595]
  • Water Permeability of Filter [ASTM D: 4491 / BS: 6906]
  • Thickness of Composite [ASTM D: 5199]
  • Tensile Strength of Core [ASTM D: 4595]
  • Grab Strength & Elongation at Break for PVD Filter [ASTM D: 4632]
  • Trapezoid Tear for Filter Component only [ASTM D: 4533]

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