Joint venture partners Bauer Spezialtiefbau and Keller Grundbau have announced that geotechnical work on rehabilitation of the Berlin State Opera building in Germany is progressing well and is expected to be completed on schedule.
Restoration of the structure has been underway since 2010 to rectify structural issues and upgrade the building to modern standards.
Work being delivered by Keller and Bauer will create a new underground structure to link the opera house with a new rehearsal centre that is being constructed nearby on a former warehouse site. The joint venture started work on constructing the 3,300m2 basement pit in June 2011 and Bauer has said the work will be completed to schedule this summer.
The work has included construction of 1,300m2 of reinforced concrete diaphragm wall, 720m2 of diaphragm cut-off wall with inserted sheet piles and 5,200m2 of secant pile wall with diameters of up to 1,200mm. In addition, 1,020 linear meters of foundation piles were sunk to depths of as much as 30m.
Although work is on target, Bauer reports that there have been a number of challenges, including discovery of a vault from a bank destroyed by bombing and both wooden and concrete foundation piles from previous development. Bauer has said that extensive jet grouting work was commissioned in a addition to the main contract to secure the opera house structure and ground freezing was also used for the stage reconfiguring work.