Bauer: mixed-in-place cut-off wall for flood protection

Bauer: mixed-in-place cut-off wall for flood protection

The Rhine is one of the busiest rivers in the world. With a total length of over 1,200 km, it is also the second-longest river in the German-speaking region.

A number of dikes along the Rhine river offer permanent flood protection, including one located in immediate proximity to the Muendelheim district in Duisburg. To give the river more room to expand at high water and thus avoid peak flows, the existing dike at Muendelheim will be relocated, creating approximately 60 ha of retention space.

In preparation for the relocation, a cut-off wall is being constructed along the line of the future dike to protect the adjacent city district from groundwater pressure. The city of Duisburg comissioned Bauer Spezialtiefbau GmbH with the construction of a mixed-inplace (MIP) cut-off wall. In this method, the soil is broken up with a triple auger, shifted, and then mixed with a binder slurry in the resulting bore hole.

"The big advantage of the MIP method is that there is no excavation. The soil doesn't have to be removed from the site; it can be used directly as aggregate. That is a definite plus, especially for the local residents,” says Mike Schwermer, project manager at Bauer Spezialtiefbau. The finished MIP cut-off wall will measure 1.6 km in length. With a width of 550 mm and a depth of up to 20 m, the total volume of the wall will be around 28,000 m³. "The strict quality requirements for the MIP wall pose a particular challenge. It must have exceptional leak tightness and a final rigidity within a specific bandwidth," explains Mike Schwermer. The cut-off wall will be constructed parallel to the Rhine river on the future

route of the dike.

Work on the project began in July 2019 using an RTG RG 25 S with MIP equipment. Bauer plans to complete the cut-off wall in March 2020.