Deep foundations with responsibility

As part of the modernization, PORR special civil engineering was commissioned with underpinning and deep foundations as early as 2024. The work was carried out in the first construction phase in accordance with the criteria of the German Sustainable Building Council (DGNB).

The rehabilitation placed high demands on those involved: confined spaces, low ceilings, work in groundwater on the Isar River, and the protection of listed buildings. To create the construction pits for the utility and technical channels, the PORR Spezialtiefbau team relied on the jet grouting method (DSV) for lateral securing and underpinning of existing foundations. A total of around 1,200 m³ of DSV structures as well as 108 micro piles with lengths of up to 15 meters and diameters of 200 to 250 mm were installed. The low-noise and low-vibration construction was a decisive advantage in the sensitive existing building. Thanks to modular steel support elements that were connected on site, a secure foundation was guaranteed even at low working heights. Micro piles are again being used in the second construction phase, which is currently underway.

Seamless interaction between different service areas

PORR Equipment Services supplied the compact drilling rigs, which are characterized by their high performance and minimal space requirements – ideal for the cramped conditions on the construction site. The team at the Colbitz site manufactured the precisely fitting steel support elements, which were designed to meet the requirements of the historic existing building.

At the same time, colleagues in the special civil engineering planning department coordinated the execution. They coordinated the processes and ensured that everything was completed on schedule.

Sustainability as a benchmark

The first phase of the modernization project received the DGNB's “Sustainable Construction Site in Special Civil Engineering” award. The award was based on an assessment of construction site organization, resource conservation, health protection, and construction quality. A special highlight: the injection binder used in the DSV columns contains biochar, which binds CO₂ and reduces the ecological footprint of the construction site. Electrical appliances ensured low-emission working conditions, and hydraulic drives operated with biodegradable oil.