Prefabricated Vertical Drain (PVD) is made of corrugated plastic core covered with geotextile. The width is typically 100 mm and the thickness are ranging from 3 to 5 mm. The installation of PVD is done through a specially constructed mast with a steel mandrel attached to an excavator to push the PVD to the required depth on a grid pattern. PVD increases the apparent mass permeability of the soft soils and thus reduces the consolidation time. It is used in combination with temporary surcharge fill to expedite the primary consolidation as well as induce several decades of secondary consolidation (creep) settlement. The main geotechnical parameters (settlements, pore water pressure, horizontal displacements) are monitored via appropriate instruments throughout the consolidation period to validate the design and ensure safe phasing for the construction of the embankment.
Menard Asia uses state-of-the-art PVD designed with high water flow capacity, high-resistance filtration properties and durable construction. Menard Asia also has developed its own fleet of PVD installation equipment to meet a wide variety of soil and site conditions. The company uses hydraulic rigs to install the PVD and has considerable experience in penetrating difficult surface layers including predrilling through stiff clays and dense sands. The PVD rigs in Menard Asia have maximum installation depth of 50 m but this can be extended if required to meet project needs.
For projects that can allow time for staged construction ranging from 6 to 12 months, the vertical drain technology can be very efficient and economic. The most common application is the linear infrastructure such as road or rail embankments. It is also usually adopted in land reclamation projects to prepare the reclaimed ground for future use (i.e., for the construction of airport runways and taxiways, marine terminals, residential and commercial buildings, etc.).