An intricate approach was needed by Soletanche-Bachy's Hungarian division HBM in forming three levels of underground parking at the Elisabeth Center development, working around a residential building scheduled for demolition at a later date.
Ground conditions on the 60m by 70m site in Budapest's old town or 7th district are typical of the area, with 3m of fill, overlying 3m of silty sand, a further 6m of sandy gravel and then stiff grey clay below 12m depth.
Groundwater is 4.5m below ground surface.
HBM keyed the diaphragm wall into the underlying clay around the perimeter of the proposed 9.4m deep excavation. Bored piles extended down 4m from the ground surface.
The residential building was essentially enclosed as an island within the site during top down construction, with much of the perimeter retaining wall supported by the uppermost basement floor slab and through which spoil from the excavation had to be removed. On the far side from the 'island building', HBM was able to install a single row of temporary ground anchors creating much needed space for the excavation.
PROJECT DETAILS Bored piles: 39, 1m diameter Diaphragm wall: 2,400m 2, up to 12m deep Jet grouting: 276m of 'jet piles' Ground anchors: 32, 21m long, 100t capacity 2,740m 2supporting slab 33,000m 3bulk excavation 2,400m 3concrete raft Two 12m deep pressure relief wells