Lakhta center :zero stage of the construction in SPb
The construction of the underground part of the Saint-Petersburg’s skyscraper should be finished by August, 2015. The construction and project managers told us about unique technological solutions and world records.
Project name: Lakhta Center
Customer: LLC “Gazprom socinvest”
Key contractors: Renaissance Construction, Samsung С&Т, Gorproect, AECOM, NIIOSP, Arabtec, Geostroy, Bauer Group, GEOIZOL, Exclusiva Design, etc.
Site: Saint Petersburg, Lakhtinsky prospect, 2, lit 3.
Time limit: 2018
Purpose: multi-purpose social and business complex
Unstable grounds make construction in Saint Petersburg extra challenge. Basically marshy soils are not quite suitable for construction of the high-rises, but with the experience of the foreign colleagues, some solutions suggested by world-known engineers helped to avoid the main obstacles and develop the sustainable design.
According to the geological survey, there are loosely stratified soils at the depth of 15-20 m. Then the hard soils start at the depth of 30 m, Vendian clays. Actually these clays are quite close to the rock soils in regard of its stiffness and consequently are suitable for stable pile-foundations.
Construction site of “Lakhta Center”. Source: multipurpose center “Lakhta Center”
Soft soil layers also make pitching of the piles difficult. However, with the ground waters being isolated, it is possible to start drilling. Pipe casing of the large diameter were used for that purpose, which prevents the water access to the digging face.
“Upon reaching the clays we go down 5 m and gain the block from clay and metal that the water does not penetrate. Then we start drilling with auger, land down the frame, concrete it. The decision was made on the base of geological survey to produce piles without bentonite in order to improve framing matters”? - comments Sergei Nikiforov, “Lakhta center” chief engineering officer.
Underground part of the “Lakhta Center” was constructed in stages: construction of the diaphragm wall, pile foundation for the pile box, creation of support disk system for the pit constructed with cut-an-cover method, raft foundation and box-shaped foundation.
Developing of the pile box for “Lakhta center”. Source: multipurpose center “Lakhta Center”
The world record of the non-stop concrete grouting was broken during the grouting of the subbase. There were poured 19 624 cu m of the concrete in 49 hours, surpassing the previous record by 3.000 cu m.
This is the largest monolithic structure made with the method of the continuous grouting. Construction director Elena Morozova explained that the structural solidity was more than of bunker designed to protect from atomic bombing.
Both local and international practices were taken in the consideration for the implementation of this unique project. While developing the project, the specialists took into consideration both local and foreign practices. «Lakhta Center» participated in the preparations for the continuous grouting in collaboration with the main contractor Renaissance Construction and detailed design developer Samsung S&T Corporation.
According to Sergei Nikiforov: “Our record is unique from the point of the managing of the process as well as from the point of technology, with the special concrete mix recipe being developed specially for this project”.
Alexander Bobkov, executive director of the “Lakhta center” comments on logistic:“Logistics was highly specified. Concrete trucks made about 2.500 runs, there were 15 transportation control point at the construction site. There were no traffic problems during the concrete transportation. No problems were caused for local citizens, most of them got information about the unique record from the news”.
According to the press office of “Lakhta Center” the zero construction stage is due to be completed by the summer of 2015.
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