With a margin of safety and reliability
Lakhta Center Project is unique from the standpoint of engineering and technical solutions. The height and weight of the tower pose special requirements to the base and foundations of the building.
Within 22 months of intensive work the builders have to build an underground structure comparable to a 25-storey building.
A box-type foundation consisting of two massive structures, each being one floor high (the upper slab is 2m, the lower slab is 3,6m) will be the base of the tower. The bottom of the foundation will be located at the depth of 20m.
In its center the structure is strengthened with traverse beams to add extra stiffness.
In its turn, the box-type foundation is mounted on 264 piles 2m in diameter and 61m long.
Each pile is an individual complicated structure and bears half percent of the loading of the future building. A very high loading is transmitted to the walls of the piles. Therefore they are deepened in a thick Vendian clay layer comparable to hard rock structure-wise.
The diaphragm wall prevents from any ingress of water.
In fact a huge five-sided glass 30m deep surrounds the foundation and generates a kind of a hydro-lock for underground waters.
Thus a unique reliability and stability of the tower base is achieved.
Solutions double-checked based on precise data
The type and structure of the foundations were selected based on the archives data and large-scale geological investigations carried out by the leading specialist companies:
• “Trest geodesicheskikh rabot i ingenernikh iziskaniy” OJSC
• NIIOSP named after Gersevanov
The assessment of the results of the in situ and laboratory tests and joint calculations of the tower base and superstructure confirmed the bearing capacity of the soil body and the reliability of the structural solutions selected.
Experienced Specialists and Modern Plant
Companies possessing unique technologies, modern high-performance and environmentally-friendly plant with highly professional specialists on staff were selected in a tender to carry out the works.
• General Contractor for the underground cycle is Arabtec Construction (United Arab Emirates)
• diaphragm wall installation “Geostroy” CJSC (Saint Petersburg)
• Piling BAUER (Germany)
Control at all the stages
At each work stage supervision of each operation is carried out.
After a well is drilled a video camera is submerged onto the bottom under each pile. So specialists can make certain that there are no water and foreign objects at the depth of up to 82m.
The consistency of concrete is checked with an ultrasonic method, the lack of any fine voids which could lead to any strain is checked. The durability of joints in cage welding is checked with ultrasound.
Scientific and technical support of the works is provided by NIIOSP named after Gersevanov.
Technical supervision is carried out by an international company, BOVIS.