ABSTRACT
The two case histories investigated are the Torhaus and Westend 1 high rise buildings on piled rafts in Frankfurt, Germany. The ground conditions of engineering interest comprise quaternary terrace sands and gravels underlain successively by the tertiary Frankfurt clay and the rocky Frankfurt limestone, see Figure 1 (Katzenbach et al. 2005). The Frankfurt clay is a stiff, over-consolidated clay with an undrained shear strength (cu) of 100 to 200 kPa (Sommer et al. 1985), suggesting that foundation behaviour is dominated by the soil stiffness instead of the soil strength.
