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Peaty, clayey and sometimes even silty soils are characterized by a high-water content, very low permeability and a low strength. When loads are applied to these soils, excess pore water pressure develops as the soil cannot adjust to the new load due to the very low permeability and slow dissipation of the excess pore water. With the dissipation of the excess pore pressures the soil adjusts to the new load. This often results in long periods (years) with high consolidation settlements and a low to insufficient safety factor on the stability of the embankment. With the application of low cost prefabricated vertical drains (PVD) a considerable reduction of the consolidation / settlement time, from years to months, and a major improvement in the stability of the embankment can be achieved. When surcharge is used, residual settlements can be controlled. The use of PVD with surcharge is therefore one of the most commonly used techniques and often the cheapest method to prepare soft compressible subsoil for future construction activities. Cofra has several consolidation systems within its portfolio. Find out more by using the links in the overview below. 

Website Diagram Consolidation Wide
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Our solutions

Cofra has the following consolidation solutions within it's portfolio

Offshore vertical drain installation

A selection of our consolidation projects

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PVD installation through very dense sand layer Chek Lap Kok Link, Hong Kong

In 2016, Cofra Singapore installed 1,600,000m1 drain up to a depth of 45m using our heavy push rig, pushing through the dense sand layer at 20m of depth without predrilling.


PVD installation highway widening SAAone A1/A6 Diemen - Almere

In 2016, we installed 7,500,000m1 of prefabricated vertical drains, with an installation depth up to 7m.


PVD installation for housing estate West Hythe phase 1-6, UK

Between 2016 and 2019, Cofra Ltd installed around 400.000 m1 of prefabricated vertical drains, each year.


PVD installation for Distribution Plot, Swindon

In 2018, Cofra ltd installed 205,000m1 of prefabricated vertical drains.


PVD installation Tuas Finger One reclamation, Singapore

Between 2016 and 2019, we installed 5,800,000m1 of prefabricated vertical drains, with an installation depth up to 35m.


PVD installation LNG plant Soyo reclamation

In 2008, we installed 2,300,000m1 of prefabricated vertical drains, with an installation depth up to 25m.