The piled raft foundation has shown its validity in the last two decades as a very economic geotechnical foundation type, where the structural loads are carried partly by the piles and partly by the raft contact stresses. The structural serviceability requirements regarding the settlements and tiltings of buildings can be fulfilled with relatively fewer piles in comparison with a pure piled foundation. This foundation system was successfully applied in stiff as well as soft subsoil. An innovative application of the piled raft is its special adjustment to cases of foundations with large load eccentricities or very different loaded parts of buildings to avoid the need of complex settlement joints especially below ground water table. Extensive measurements of the load transfer mechanism of piled raft foundations during and after the construction were performed to verify the design concept and to prove the serviceability requirements. Calculation procedures to model the behavior of such complex three-dimensional problems have been developed since the 1970s (e.g., by Butterfield and Banerjee 1971, Poulos and Davis 1980 and Randolph 1983). But some important requirements concerning the raft stiffness, the nonlinear behavior of the pile support and the slip developing along the pile shafts even under working loads were not sufficiently considered in these analyses. For these reasons an improved numerical model based on a mixed technique of the Finite Element Method (FEM) and the Boundary Element Method (BEM) was developed taking into account all above mentioned effects. The results of measurements and of the developed calculation method will be shown and compared in a short overview.
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