American Society of Civil Engineers


Investigation on the Requirements Regarding the Minimum Embedded Length of Monopiles


by Yu-Shu Kuo, (Assistant Professor, Department of Civil Engineering, National Pingtung University of Science and Technology, 91201, Pingtung, Taiwan. E-mail: kuo@mail.npust.edu.tw), Martin Achmus, (Head of Institute, Professor, Institute of Soil Mechanics, Foundation Engineering and Waterpower Engineering, Leibniz University of Hannover, 30167, Hannover, Germany. E-mail: achmus@igbe.uni-hannover.de), and Khalid Abdel-Rahman, (Senior Lecturer, Dr.-Ing., Institute of Soil Mechanics, Foundation Engineering and Waterpower Engineering, Leibniz University of Hannover, 30167, Hannover, Germany. E-mail: khalid@igbe.uni-hannover.de)
Section: Section 3: Innovative Foundations, pp. 315-324, (doi:  http://dx.doi.org/10.1061/41106(379)40)

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Document type: Conference Proceeding Paper
Part of: Deep Foundations and Geotechnical In Situ Testing
Abstract: Monopiles are open-ended steel pipe piles with diameters of usually 3 to 5m, which are used as foundation structures for offshore wind energy towers. Such foundations are subject to intensive cyclic horizontal loading due to wind and wave loads. In the practical design different requirements regarding the minimum embedded pile length are used in order to limit the lateral deformation under static and in particular cyclic loads. Such are the "critical length", "vertical-tangent" and "zero-toe-kick" criteria. For piles of very large diameter and thus high stiffness like monopiles these criteria lead to very large and hardly realistic required lengths. In this study, the different design criteria are compared with respect to piles of very large diameter. By means of the stiffness degradation method, a method which makes the determination of displacement accumulation with cyclic loading possible, the different criteria are assessed. With that, the suitability of adopting the mentioned design criteria for monopile foundations is discussed.


ASCE Subject Headings:
Pile foundations
Pipe piles
Offshore structures