Berlin, Palais an den Ministergärten
|Company||Stump-Franki Spezialtiefbau GmbH|
|Principal||MUC Areal Bau GmbH|
|Location||Berlin - Germany|
|Type||Specialist civil engineering|
|Runtime||01.2019 - 12.2020|
Construction pit, diaphragm wall, jet-grouted floor slab and anchor.
MUC Areal Bau GmbH is planning a commercial and residential building at Cora Berliner Strasse 2. Stump-Franki was contracted to build a 9.5m-deep construction pit for the project. The plans called for a construction pit wall comprising in-situ concrete diaphragm walls with a single layer of strand anchors. Horizontal sealing was to be implemented through the existing marl layer at depths of up to 2.0m as a natural dam layer. The construction pit was divided into three sections by additional thick bulkheads to minimise the risks posed by possible leakages in the natural dam to construction time and costs.
Remains of old bunkers discovered
The subsoil survey noted the discovery of old air-raid shelters on the site, representing man-made obstacles to the project. These obstacles were overcome during the clearing of the line by overlapping large-scale boring (d = 880mm). The bunker remains within the construction pit were
demolished later in the process and removed with the excavated soil. This was when another, previously unnoticed air-raid shelter was discovered. After an investigation into the historic significance of the building, this was also dismantled and the part of the bunker outside the construction pit was filled with liquid soil.
Additional jet-grouted floor slab required
An additional challenge was presented by natural obstacles encountered during the diaphragm wall construction of the natural dam layer. It also became apparent during the diaphragm wall construction that the dam layer was insufficient in some areas. As a result, additional thick bulkheads and 600m² of additional jet-grouted floor slab were required.
In spite of these impediments and additional performance requirements, outstanding cooperation amongst the Stump-Franki construction site team saw the construction pit handed over to the client two weeks ahead of the agreed deadline.
Technical data / quantities
Diaphragm wall area
Diaphragm wall dimensions
d = 600mm / to depths of 17m
Jet grouting jet lengths
up to 12m
Looking into the finished construction pit.