- To characterized monopile’s behavior under cyclic load through centrifuge tests. Driven piles in dense Fontainebleau sand submitted to transversal loads will be studied.
- To create a database of monopiles tests in a geotechnical centrifuge.
The global behavior of a pile under lateral cyclic load is a complex subject. The soil structure interaction will evolve cycle per cycle depending on the level of strain (and therefore depending on the depth).
To develop a numerical model capable to represents a monopile behavior, experimental data are required. Centrifuge tests allow studying the global response of a pile by considering the vertical gradient of geostatic stress and the pile installation. Another important advantage of performing centrifuge tests is that it is possible to apply a monotonic load, until failure, to a pile with the same characteristics as the ones study under cyclic load. In a first step, monotonic loading will be performed to assess the initial soil structure interaction reference. Cycles will then be applied to assess the degradation of the interaction (mainly initial stiffness and ultimate resistance) as a function of the number of cycles and the properties of the applied cycles.
Many experimental programs at the IFSTTAR centrifuge have been performed to study offshore wind turbine piles:
- National project SOLCYP
- Regional projects FONDEOL and CHARGEOL
- Internal projects (Ph.D and post-doctoral fellowships)
In the SOLCYP+ project a monopile of true scale, 10 to 30 m depth, and 4 to 10 m diameter with a relatively low diameter/height ratio ranging from 5 to 2, will be simulated at a reduced scale of 1/100. Pile’s instrumentation will measure bending moments and displacement at the ground level. Data from tests will allow building the p-y curves used to dimension a monopile under lateral loading.