A Bauer BG 30 in the center of Munich

Bauer Spezialtiefbau constructs excavation pit for office and commercial building in Munich’s Central Station district.

In the center of the Bavarian capital and directly adjacent to Munich Central Station a new commercial and office building is currently being constructed on a demolition site. Since April 2022, Bauer Spezialtiefbau GmbH has been constructing a retaining structure with a total of 298 piles using the double rotary drilling system (FoW) in the newly vacated site on behalf of PI Projekt Bayerstraße 25 GmbH & Co. KG, a joint venture of the companies Bauwens and Büschl as well as ehret+klein.

What makes this drilling method unique: the combination of fully cased drilling with an internal, continuous auger. “The piles reach up to a depth of 18 m below the surface and are being constructed with a diameter of 620 mm using a Bauer BG 30,” explains Nicolai Gügel, Site Manager for Bauer Spezialtiefbau GmbH. “The excavation pit itself is being excavated to a depth of roughly 10.5 m.” In addition, anchor work is being executed with up to seven strands in two layers – in part below the groundwater level as well – along with strut work.

For this work, the excavation pit level was lowered by roughly 1.5 m and an auxiliary retaining structure was installed with lightweight profiles and trench sheets. Another challenge with this project is that three subway tunnels run directly beneath the excavation pit, which is why it cannot be excavated completely or in a single operation. “For this reason, the workspace is divided into sections that are excavated successively in different phases and secured with pit sheeting,” says Nicolai Gügel in conclusion.

The main work of Bauer Spezialtiefbau GmbH is expected to be completed in November 2022; including all demolition measures, the project will last until January 2024.