Injection

Innovative Injection Hose protects the Nordhavnsvej Tunnel from Baltic Sea Water Pressure

Nordhavnsvej-Tunnel site view

WaterproofX 100 is a novel hexagonal injection hose made of a special plastic, which is distinguished above all by its easy processibility. It takes over the function of transport line, through which the grout material is injected after concreting

HauCon delivered more than 3,000 m of WaterproofX® 100 injection hose from StekoX® to the construction site

The 4-lane Nordhavnsvej Tunnel is currently one of Copenhagen’s biggest construction projects and belongs to the Nordhavnsvej-Vej-og Tunnelenterprise major scheme. It underpasses the Danish capital over a length of 1.65 km with 24 m diameter from the Helsingore motorway to Strandvaenget. A 620 m long section with a diameter of 25 m runs below sea level at a depth of up to 22 m. It was decided to use the special injection hose WaterproofX^® 100 from StekoX® to seal the working joints.

The huge highway and tunnel complex is intended to relieve the inhabitants of Copenhagen and neighbouring Gentofte of noisy traffic from 2015. The Nordhavnsvej Tunnel part-project was awarded by the City of Copenhagen to the Joint Venture E. Pihl & Son A.S. (Pihl), Denmark and Züblin A,S., Denmark. Work on the tunnel commenced in 2011. It is due to last 4 years and the tunnel will open in 2015. Around 160 million € is earmarked for the tunnel. The road complex’s geometry had first to be geared to the high buildings, existing rail traffic and the alignment of the “Strandvejen” highway and planned correspondingly. The tricky North European glacial geological general conditions are seen as a particular engineering challenge.

The concrete for the 620 m long tunnel section below sea level, produced by cut-and-cover, requires special waterproofing to withstand the Baltic Sea’s water pressure. The HauCon Company, which provides technical solutions, thus proposed the injection hose WaterproofX 100 to seal the working joints. The hexagonal injection hose’s cross-section is strongly reminiscent of a honeycomb and offers an optimal ratio of wall material to volume. The hose possesses micro-openings through which the injection material passes easily to fill pores and cracks in the concrete. Thanks to the wall thickness, material composition and geometry of WaterproofX 100 only slight overpressure of 1 bar is needed to inject the waterproofing material into the working joints so that they are permanently sealed.

The injection hose is easy to lay and can be simply cut to size thanks to the markings along its length. It is suitable for all injection agents available on the market. Consequently planners are not restricted when it comes to choosing the injection material.

The supplier HauCon A/S, Lystrup, Denmark delivered more than 3,000 m of WaterproofX 100 injection hose from StekoX including the complete accessories to the construction site. This will be laid by the end of the scheme. No problems cropped up during the grouting sessions tackled so far. The contractors’ feedback was thoroughly positive. StekoX consulted intensively with all those involved directly on site prior to laying. The particular advantage of the new hose system is that it is possible to carry out multiple injecting even given 30 m overlength. This signified many technical advantages for the concrete tunnel project.

In this connection, StekoX, the Magstadt-based company, as manufacturer and supplier of the injection system, engendered confidence and would be able to undertake the grouting as service provider for the remaining injection hose sections still to be tackled. In addition StekoX was also able to prove its know-how in tunnelling thanks to comparable reference projects in Asia and Europe.