We have distributors around the world. Just send us a mail and we quickly direct you to a local distributor. Send mail >>
TUNNEL SEGMENT GASKETS
The importance of hydrophilic cords
Back to overview
The gaskets placed between lining segments in many tunnels are a vital component in ensuring a long and useful life for the tunnel by protecting the lining and the tunnel interior from ingress of groundwater. That’s why they are being used on a big scale by tunnel builders worldwide. However, more and more tunnel builders are buying tunnel segment gaskets with a hydrophilic cord that swells on contact with moisture. In this article, we explain you why the use of tunnel segment gaskets with hydrophilic material is booming, especially in the Middle East.
PROBLEMS WITH CLASSIC TUNNEL SEGMENT GASKETS
When you look at a section of a classic tunnel segment gasket (most of them are made from extruded EPDM rubber), you can see a cell structure that allows the gasket to be compressed as the segments are installed and pushed together during installation of a lining ring. The pressure between these gaskets protects the tunnel from groundwater infiltration.
But during their lifespan, insufficient pressure between the tunnel segment gaskets can occur, making it possible for groundwater or moisture to infiltrate in the tunnel. Failure appears to come from gaskets being incorrectly installed, damaged during transportation, or rendered inefective due to spalling of the concrete on the outside of the gasket.
Moreover, as the trend towards deeper and deeper tunnels increases, tunnel segment gaskets must withstand higher groundwater pressures.
THE POWER OF HYDROPHILIC TUNNEL SEGMENT GASKETS
That's why more and more tunnel builders switch to tunnel segment gaskets with a hydrophilic sealing insert (or a hydrophilic cord). In case insufficient pressure between the tunnel segment gaskets occurs, the hydrophilic sealing insert works as a kind of backup.
Hydrophilic sealing inserts swell automatically in contact with moisture or water. By swelling, the pressure between the tunnel segments is restored and the tunnel is waterproof again.
HYDROPHILIC TUNNEL SEGMENT GASKETS: EXAMPLES
The Red Line Metro line in Doha, the Qatari capital, is an enormous tunneling project that took advantage of hydrophilic tunnel segment gaskets. No fewer than a million (!) meters of hydrophilic sealing inserts were used to waterproof the tunnel segments.
However, standard hydrophilic sealing inserts are not eligible for use in most areas of the Middle East, because the groundwater is extremely salt there. This reduces the swelling capacities of these sealing inserts dramatically.
That’s why the engineers of the Red Line Metro approached BeSealed®, the Belgian producer of hydrophilic waterstops, to develop a custom made hydrophilic sealing insert for tunnel segment gaskets. BeSealed® managed to develop a hydrophilic insert that maintains its swelling capacity, even in water with extremely salt concentrations (up to 10%). BeSealed® is selling this unique sealing insert now as the Polybar+ SuperSwell.
