Soil-structure interaction of deep excavations in urban environment

In urban environment deep building pits often have to be excavated in direct neighbourhood to existing high-rise buildings. In order to guarantee the stability and the serviceability of the adjacent sensitive structures new conceptions for the excavation technology and for the reliable prediction of the deformations caused by the excavation have to be developed especially for soft ground like the Frankfurt Clay, a highly plastic clay of medium consistency. Taking into consideration the long-time experience gained with tied-back sheetings of excavations in Frankfurt/Main, on two examples of deep excavations it will be explained how advances in analysis, excavation technology and field monitoring can improve safety and minimize movements effectively. Both excavations for the foundation of two new high-rise buildings reach depths of up to 21 m below surface and are based on modified top/down construction technologies. The results of computational prediction and carefully monitored performance are presented showing the soil-structure interaction of deep building pits in soft clay adjacent to existing high-rise buildings.s