Securing a foundation pit for multifunctional building Dominant in Bratislava-Petržalka

The Zakládání staveb Co. has currently carried out works on securing a foundation pit for the construction of a multifunctional building Dominant in the centre of the Petržalka housing estate. The construction site is limited on three sides by busy roads; the fourth side leads to a green area and a parking lot nearby a block of flats. Securing of the foundation pit is carried out in a form of closed sheet pile cofferdam to provide protection against a high groundwater level.

The works started by a pre-excavation to the depth of 4 m below the surrounding ground level, i.e. approximately 30 cm above the groundwater level. The pre-excavation walls are secured by nailing and sprayed concretes. The sheet pile toes are fixed into neogenous clay located in the depth of 12-17 m below the working platform. There are two types of sheet piles used according to the depth of the clay location: VL 604 that is 14 m long or AU 16 used in the lengths of 14, 15, 16, 17 and 18 m. The method of direct infloating with the advantage of diminishing skin friction of vibrated elements is used to facilitate driving of these sheet piles.

Because of the requirement for maximal use of the foundation pit the sheet piles are driven in close proximity to the pre-excavation face where they come to the collision with a relatively large vibrating driver; at several places it is therefore necessary to do additional ramming on the sheet piles with an impact hammer that is not so wide. Another extra work enforced during the construction was securing an excavation of sewerage relocation that passes through the construction site. Here again the technology of driving was used to carry out a sheet pile wall of sheet piles type VL 604 - 6 m long, to the length of approx. 40 m.

The following machinery has been used at the construction site:
Driver carrier crane LIEBHERR
Vibrating driver PTC 30
Driver carrier RDK 300
Impact driver HPH 1200
Infloating equipment NETSCH

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