Ground improvement versus hybrid foundation and deep foundation – Comparison of foundation concepts for three case histories of European significance

The focus of the keynote paper is on the comparison of different foundation concepts for three case histories of European significance. The stadium in the Austrian city of Klagenfurt was designed and built for the EURO 2008 (Austria and Switzerland) in slightly consolidated soft lacustrine clays. The shallow foundation rests on floating stone columns installed with the vibro replacement technique allowing controlled large time-dependent settlements. For the Combined Cycle Power Plant Malženice near Bohunice (Slovakia) a hybrid foundation concept was executed in collapsible aeolian silt deposits (loess). The ground was initially improved by the vibro replacement technique and the final cementation of the stone columns produced deep foundation elements. The new spectacular cable-stayed bridge over the Sava River is the new landmark of Belgrade (Serbia). The 200 m tall pylon of the 965 m long bridge rests on a closed box foundation made of a clasping diaphragm wall and large-diameter bored piles inside. Thus, the highly concentrated loads are deeply transferred into the overconsolidated marls. The different foundation concepts are compared and discussed. It is illustrated that all the concepts are justified taking into account the ground conditions, structural and serviceability requirements of the buildings, and economical factors (time and cost).