Simulation of the Plug inside Open Steel Pipe Piles with Regards to Different Installation Methods

Open steel pipe piles are used for various applications in costal engineering and port structures and they are becoming increasingly more important for offshore structures. A plug formed during the installation of open steel pipe piles has an influence on the installation process of the steel pipe pile as well as on the final bearing behaviour and the pile resistance. Forming of the plug depends on different influences, e.g. the pile diameter, the soil conditions and the installation method. To obtain a better understanding of the formation of the plug and its consequences several experimental small-scale tests, experimental field tests and numerical simulations have been performed. But so far this phenomenon is not completely investigated yet. At the beginning of this paper a structured overview about the characterization of the plug as well as soil mechanical processes during the pile installation in non-cohesive soil are provided. Then, the results of a centrifuge study are shown. The focus of this paper is the numerical simulation of the installation process of impact and vibratory driven piles in non-cohesive soil to investigate the effect of plugging with regard to different installation methods. Centrifuge experimental results are utilized to validate the numerical model, which can provide detailed insights into the physical processes occurring in the soil but are difficult to measure in experiments. The numerical analyses hence illustrate zones of densification/loosening, which highlight the differences resulting from the installation methods.