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Excavations for the “Sechs Freunde” (‘Six Friends’) housing project

Photo: A construction machine creates the diaphragm wall. The scoop can dig a narrow, vertical pit. There are silos in the background.
Facts and Figures
Company FRANKI Grundbau GmbH & Co. KG
PrincipalAurelis Real Estate GmbH & Co. KG
LocationHamburg - Germany
Type Specialist civil engineering
Runtime11.2016 - 06.2017

Excavation pit for the crane-constructed “Sechs Freunde” (‘Six Friends’) housing project in Hamburg-Altona

“Sechs Freunde” is the name of the planned residential complex which is to be built on former railway land in Hamburg-Altona. In six buildings - each with eight storeys - a total of 242 apartments for rental, as well as four commercial units, will be built above a shared underground car park. With their upper four floors, the “crane constructions” will tower approximately ten metres above the historic store houses.

FRANKI was commissioned with the creation of the entire excavation pit. The soil is very heterogeneous, and contains sandy fillings, expansive boulder clay and moraine clay with irregular alternation and various consistencies, as well as water-bearing fine and medium sand. The groundwater is mainly found below the planned base slab.

The 5,200 m² excavation pit had to be up to 8.50 m deep. The shoring could be implemented on the street side with a simply anchored soldier pile wall. A partially doubly anchored diaphragm wall was constructed along the walls of the store houses. In the final state, the diaphragm wall will serve as a foundation element of the projecting crane constructions. The excavation pit was created in two phases, so that the first part could be handed over to the shell constructor in May. At the beginning of July, the excavation pit was handed over, fully on-schedule. 


  • 5.750 m² diaphragm wall, d = 60 cm, t ≤ 35 m
  • 2.040 m² soldier pile wall
  • 312 temporary multi-strand anchors, Zk ≤ 510 kN, L ≤ 21 m
  • Ca. 30.000 m³ excavated soil and disposal, water retention,
  • probing of anchor and carrier routes