Verticale Drainage en V0(2)

7/31/2019 Verticale Drainage en V0(2)

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MebraDrainverticaldrainage

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MebraDrainvertical drainagec

The ground level after the installation of vertical drainage

GPS logger

The technology

Vertical drainage has been in use in its current orm since the 1970s. Vertical

drains are used to considerably reduce construction time. Over the years,

the installation technique has improved to the extent that Cora has installed

millions o metres o drain per year and can oten be ound working on the

largest and most challenging projects.

Why vertical drainage?

I loads are applied on clay and peat layers, the po or permeability o the layers

can lead to excess pore water pressures. I no measures are taken, this ex-

cess pore water gradually dissipates and a slow and continuous settlement is

measured. This also gives rise to possible stability problems i embankment

construction takes place too quickly. Coras MebraDrain system consists o a

plastic strip drain that is installed vertically rom ground level down to the de-

sired depth. This creates vertical drainage paths in the subsoil, considerably

reducing the ow path o the excess pore water. As a result, the consolidation

process can be reduced rom decades to six months or less and the stability

is increased, meaning that embankment construction can take place more

quickly.

Cora is a proven partner in the feld o civil engineering or the installation o innovative ground improvement

products. Being able to respond proactively to customers requests, in some cases with equipment devel-

oped in-house, makes Cora a prominent market leader and contractor with an international customer base.

Cora has international establishments (depots/outlets) rom which equipment can be shipped to p rojects all

over the world. Years o experience, in-depth knowledge and many suc cessul projects ensure that Cora is a

contractor that is in great demand and a market leader in the installation o ground improvement products.


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MebraDrainvertical drainage

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Polypropylene core

Filter matting

Installation of the infrastructure with the aid of vertical drainage on the Second Coen Tunnel project, Amsterdam, The Netherlands

Installation of vertical drainage in the Westrandweg project, Halfweg, The Nethelands

Installation

The vertical drainage is installed by Cora using patented stitchers developed

in-house and constructed exclusively or Cora. Using this stitcher a steel

profle (mandrel) containing the drain is inserted. This lance is moved up and

down by a system o cylinders or winches driven by the hydraulics o the

hydrolic excavator. The drain that protrudes rom the underside o the lance

is attached to an anchor plate. This anchor plate ensures the sealing o thelance so that soil cannot get inside during the installation process. It also

takes the drain down to the desired depth. When the lance reaches the de-

sired depth the lance is retracted. Due to the resistance experienced by the

anchor plate when the lance is retracted, this anchor plate and thus also

the underside o the drain remains at the desired depth. Ater the lance has

returned above ground, the drain is cut o and a new anchor plate is astened

to the underside o the next drain.

Applications of vertical drainage include:

> Preparation o residential districts or construction

> Installation o inrastructure (roads, railways, ports and airports)

> Installation o dikes

> Land reclamation projects

Advantages of vertical drainage:

> Little disruption o the various soil layers

> Guaranteed water drainage, even in the case o high soil pressure and

> deormation

> Possible adaptation o the core and flter matting to the soil properties

> Short consolidation period thanks to the use o small drain spacing

> Quick installation: on average 8,000 metres per day, per machine

> No water necessary during installation

> Installation to a drain depth o 65 m

> Installation checked with the aid o a drain logger

> Clean implementation, no waste soil is generated


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Runway, motorway, railway Topping Vertical drain platform

Sand layer Vertical drains Clay layer Settlement layer

Cofra

Cora B.V. is an innovative contractor specialising in ground improvement tech-

niques and membrane construction. Quality is everything to us and thanks to

our high level o experience and expertise we can provide the entire pro-

cess rom design to implementation all under one roo. Cora, and, its sister

company Geotechnics, is part o the internationally operating company Royal

Boskalis Westminster. Cora is active in specif c sectors o civil engineering,

ground improvement techniques and geotechnical hydraulic and gas barriers.

Cora is always working on the development o new ground improvement

techniques.

Other Cofra techniques:

> AuGeo

> Geolock

> BeauDrain-S

> HDPE

> CDC

You can fnd urther inormation about vertical drainage and other techniques

rom Cora on our website www.cora.com.


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T +31 (0)20 693 45 96, F +31 (0)20 694 14 57

www.cora.com, [email protected]

Cora BV, P.O. Box 20694, 1001 NR Amsterdam

The Netherlands

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Verticale Drainage en V0(2)

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