Bauer uses lift cell method for city development
By Leila Steed14 April 2021
Civil engineering firm Bauer Spezialtiefbau has used its lift cell method to complete the piling works for a new city area currently under construction in Copenhagen, Denmark.
The ‘Postbyen’ development project will see new office buildings, hotel apartments and retail, residential and commercial spaces built in the centre of the country’s capital city.
Bauer’s lift cell method allows the settlement of bored piles to be determined before they are installed. It is an enhancement to the company’s capsule press, which is used to measure force and for the pre-stressing and strutting of excavation pits.
According to the company, its lift cell is “an interesting solution for projects with a low permitted total settlement or low permitted differential settlements between adjacent piles.”
Made of stainless steel, lift cells are a type of hollow cushion that are secured to the bottom of each pile’s reinforcement cage. They are then encased in concrete and, once the concrete has hardened, they are filled with high-pressure water via hydraulic lines.
Bauer said, “The pressure used in this process is generally determined individually for each pile. After a prescribed retention time for the hydraulic pressure, the lift cell is first entirely filled with a cement paste that has been tested to ensure its suitability until the planned quality is achieved.
“Then another injection is carried out so that after the cement paste has hardened, deformations of the lift cell are permanently excluded and the pile is fully pretensioned.”
The company, which started the piling works in December 2020 and finished in February 2021, delivered, installed and injected a total of 101 lift cells for the Postbyen project.
Dr Joerg Zimbelmann, team leader of the Geotechnics Division in Bauer’s Structural Engineering Department, said, “Depending on the project requirements, the lift cells are produced by our certified manufacturer with individually defined diameters and undergo a special quality inspection”.
Bauer’s work on the Postbyen project saw it use two sizes of lift cell. For larger 1,500mm diameter bored piles the company 35 1,300mm lift cells and for the project’s 1,180mm diameter piles it used 66 lift cells with a diameter of 1,000mm.