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ARGE North-South Urban Railway Cologne, Germany

The project:


Construction of the north-south urban railway, Cologne, south section


Executing companies:

Wayss & Freytag Ingenieurbau AG

Ed. Züblin AG


The section is about four kilometres long. By far the largest section of the route is underground in two single-track tunnels that run parallel to one another.


First problem:


Slot walls up to 45 metres in depth were created. During the building phase the slot walls were filled with bentonite support fluid. In order to cast the slot walls, the ratio of sand in the bentonite must not be greater than 3%. For this reason, the bentonite and sand mixture is pumped to a separating system. There the sand part of the mixture is filtered out, and the regenerated bentonite suspension is reused.


Our solution:


Use of a GPN3-80 agitator pump mounted in a slot wall cage.


Second problem:


Two shafts were drilled near the Old Market (Alter Markt). From here the foundations of the adjacent residential buildings were stabilised. In doing so, various cross drillings are drilled to a depth of up to 50 metres depending on the shaft. Next, the boreholes are injected with a cement suspension. In the case of the boreholes as well as the injections the slurry that collects is diverted out of the shaft using a submersible pump.


Our solution:


Use of an NKZ3-100H agitator pump.

The NKZ series is especially well-suited for pumping abrasive suspensions.

In the event of abrasive and corrosive utilization, stronger wear and tear will take place naturally in certain components. With regards to the above application wear and tear can take place mainly in impeller, agitator, suction plate, shaft sleeve, oil ring, mechanical seal, pump casing, strainer, motor casing and discharge coupling. Depending on the working conditions the lifetime of those parts might vary significantly and can be shorter than the legal warranty period.
In this regard, please pay attention to our general terms and conditions that we also send to you by mail on request.