Study of the shaft friction degradation of piles under cyclic axial loading in wind turbine foundations

• Grant number: 17/07341-9
• Support Opportunities: Scholarships in Brazil - Master
• Start date: November 01, 2017
• End date: June 02, 2019
• Field of knowledge: Engineering - Civil Engineering - Geotechnical Engineering
• Principal Investigator: Marcos Massao Futai
• Grantee: Andrei Nardelli
• Host Institution: Escola Politécnica (EP). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Due to the growing efforts for achieving a sustainable development, the wind energy displays an important role worldwide. As a result of the increasing size of wind turbines and wind towers, the onshore wind turbine foundations will be subjected to higher static and cyclic forces and, therefore, the use of pile group foundations will be more recurrent. This group of piles transfers the load through the bearing and pullout capacities of opposites piles. However, many studies indicate that cyclic axial loaded piles have their capacity decreased mainly due to the reduction in shaft friction. These studies focused their research on a limited number of cycles and considerable cyclic loading amplitudes. Hence, the main objective of this research project is the investigation on the behavior of the soil-pile interface when subjected to a high number of cycles considering different cyclic loading amplitudes. Cyclic direct shear tests with constant normal stiffness on sand-concrete interfaces will be performed regarding the parameters that affect this degradation: state and nature of the soil; interface roughness; number of cycles; normal stiffness imposed; cyclic loading amplitude; and saturated, unsaturated and dry soil conditions. The results obtained will be statistically analyzed and, through a literature review, will be validated. Finally, this study will be used to substantiate the soil constitutive models in soil-pile interface behaviour simulations on onshore wind tower foundations in Brazil, enchancing quality of the projects and performance of these foundations during its lifespan. (AU)

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

NARDELLI, ANDREI; CACCIARI, PEDRO PAZZOTO; FUTAI, MARCOS MASSAO. Sand-concrete interface response: The role of surface texture and confinement conditions. SOILS AND FOUNDATIONS, v. 59, n. 6, p. 1675-1694, DEC 2019. (17/07341-9)

ANDREI NARDELLI; MARCOS MASSAO FUTAI. Avaliação de fundações de turbinas eólicas terrestres brasileiras. Rev. IBRACON Estrut. Mater., v. 15, n. 5, 2022-03-28. (17/07341-9, 15/10223-2)

Academic Publications

(References retrieved automatically from State of São Paulo Research Institutions)

NARDELLI, Andrei. The shaft friction degradation of piles under cyclic axial loading in wind turbine foundations.. 2019. Master's Dissertation - Universidade de São Paulo (USP). Escola Politécnica (EP/BC) São Paulo.