Special drain used for tunnel lining rehabilitation
Location of work/project:
Germany - Hamburg, St. Pauli tunnel
Low & Bonar
Proven performance no doubt is one of the biggest advantages of EnkaDrain CK20. Pre-cutting to length as well as the supply only shortly before installation were amongst the benefits supporting the specification of EnkaDrain CK20 for this project.
The With two tubes stretching over 426.5 meters, the St. Pauli Elbe Tunnel crosses below the river Elbe. Construction started in 1907 and was not completed until 1911. After a major overhaul in the 1990s, the rehabilitation of the eastern tunnel tube using EnkaDrain CK20 began in 2010.
More often than not the rehabilitation of existing structures is a more complex endeavor than new developments. This is particularly true for listed buildings. In the case of the St. Pauli Elbe Tunnel, space restrictions called for tailored solutions. Contractor was looking for a reliable system to drain off occurring seepage water, one that would endure the shotcreting process without concrete getting into the drainage core, also a frictional connection between the new lining and the existing construction was to be avoided.
In EnkaDrain CK20 is a multifunctional geocomposite for drainage and lost shuttering/ sealing. Its three-dimensional monofilament core is attached to a water permeable nonwoven filter on one side and a concrete or shotcrete tight PVC layer on the other. With a discharge capacity of 3.2 l/sm the product exceeded the seepage water drainage requirements calculated for this project. Thanks to its specific properties the drainage core remains flexible even when under pressure and the composite could be used to prevent friction between the new liner and the existing construction.
Facing inwards, the product’s PVC fabric allows the composite to serve as a sealing. As with most other projects the PVC fabric overlaps were welded so that no concrete slurry could enter the drainage core during the shotcreting process. To master the prevailing space limitations, EnkaDrain CK20 was supplied pre-cut. Also material was delivered to the site almost “just in time” making stocking of larger quantities redundant.
Installation of the composite is fast and easy and it can be fixed on any subsurface.