Experimentelle Erkenntnisse zum zyklisch axialen Pfahltragverhalten

Experimental findings on pile behaviour under cyclic axial loading.

It is known that cyclic axial loads may lead to the accumulation of plastic pile displacement and to the change in post-cyclic pile capacity, but the causative mechanisms of cyclic pile behaviour are not completely understood. Thus, within the framework of a project supported by the German Research Foundation (DFG), the cyclic and post-cyclic pile behaviour was systematically investigated using three experimental concepts. This paper reports about the investigation techniques and the significant findings of test results: In 77 model tests loading parameters and soil properties were modified. In this way it was possible to identify key influence factors for the accumulation of plastic pile displacement and for the change in post-cyclic pile capacity. Based on stress measurements and observation of soil mechanical mechanisms using Particle Image Velocimetry (PIV) different hypothesis for cyclic and post-cyclic pile behaviour could be derived. Finally, in order to forecast the plastic pile displacements from a qualitative viewpoint, a novel interaction diagram is presented.