Background
The SVH project joins the experimental studies realized with the geotechnical centrifuge of IFSTTAR in marine geotechnics, since the studies of foundations for offshore platform until the foundations of structures of power productions at sea.
The pile driving in geo-centrifuge is at present limited by the stroke of the available jacks; with the new SVH addressed in this project, the simulation of the installation phase of a pile (before loading) will be completed.
The envisaged servo-jack is similar to its 2 predecessors of whom IFSTTAR (section of 50×220mm ², capacity of 3200daN), but with a more important stroke of 450mm (against respectively 70 and 300mm).
Besides the stroke, the expected performances are speeds between mm/s 0.002 and 130 and the possibility of realizing cyclic loads typically of ±1mm at 20Hz.
Scientific advances and innovation
The main interest of this device is to be able to take into account during the installation of a pile by jacking of the real modifications of the stress state around the pile. The jacking during flight in the geo-centrifuge is so very close to conditions met in situ.
Expected technical and economic impact
The experiments on centrifuged small-scale model allow to realize rather easily (and thus in very low costs in comparison to in situ) parametric studies on the behavior of the foundations, for example under cyclic loading.
Moreover, studies carried out with this device should make it possible to avoid oversizing the foundations of “high power” wind turbines according to site conditions and thus reduce their cost in the long term.
Key project milestones
- 2017 - Order and delivery of the equipment
- 2018 - Applications from 2018, in particular within the framework of Ismat El Haffar's thesis carrying on the " physical modelling and study of the offshore behavior of the deep foundations of wind turbines ", co-financed by the Region of Pays de la Loire.
Demonstrator
It is an equipment in itself which does not require demonstrator’s intermediate phase. The jacks of lower stroke already used in centrifuge have already shown their robustness in macro-gravity.
Prospects
Thanks to this device, it will be doubtless possible to explore more easily the behavior of piles under cyclic loads (establishment of diagrams of stability). This SHV will be used also certainly in the thesis in project on the foundations offshore, which can begin in September, 2018.
